diff --git a/README.md b/README.md
index 2a49720..7ce862c 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,7 @@ For details on the new smoke test strategy and contributor guidance, see [TESTIN
 - **Smart Republishing**: Automatically republish listings at configurable intervals to keep them at the top of search results
 - **Bulk Management**: Update or delete multiple listings at once
 - **Download Listings**: Download existing listings from your profile to local configuration files
+- **Extend Listings**: Extend ads close to expiry to keep watchers/savers and preserve the monthly ad quota
 - **Browser Automation**: Uses Chromium-based browsers (Chrome, Edge, Chromium) for reliable automation
 - **Flexible Configuration**: Configure defaults once, override per listing as needed
 
@@ -198,6 +199,7 @@ Commands:
   delete   - deletes ads
   update   - updates published ads
   download - downloads one or multiple ads
+  extend   - extends active ads that expire soon (keeps watchers/savers and does not count towards the monthly ad quota)
   update-check - checks for available updates
   update-content-hash – recalculates each ad's content_hash based on the current ad_defaults;
                       use this after changing config.yaml/ad_defaults to avoid every ad being marked "changed" and republished
@@ -221,6 +223,11 @@ Options:
         * all: downloads all ads from your profile
         * new: downloads ads from your profile that are not locally saved yet
         * <id(s)>: provide one or several ads by ID to download, like e.g. "--ads=1,2,3"
+  --ads=all|<id(s)> (extend) - specifies which ads to extend (DEFAULT: all)
+        Possible values:
+        * all: extend all eligible ads in your profile
+        * <id(s)>: provide one or several ads by ID to extend, like e.g. "--ads=1,2,3"
+        * Note: kleinanzeigen.de only allows extending ads within 8 days of expiry; ads outside this window are skipped.
   --ads=changed|<id(s)> (update) - specifies which ads to update (DEFAULT: changed)
         Possible values:
         * changed: only update ads that have been modified since last publication
diff --git a/src/kleinanzeigen_bot/__init__.py b/src/kleinanzeigen_bot/__init__.py
index 1819722..52758cf 100644
--- a/src/kleinanzeigen_bot/__init__.py
+++ b/src/kleinanzeigen_bot/__init__.py
@@ -4,6 +4,7 @@
 import atexit, enum, json, os, re, signal, sys, textwrap  # isort: skip
 import getopt  # pylint: disable=deprecated-module
 import urllib.parse as urllib_parse
+from datetime import datetime
 from gettext import gettext as _
 from pathlib import Path
 from typing import Any, Final
@@ -309,6 +310,26 @@ class KleinanzeigenBot(WebScrapingMixin):
                         LOG.info("############################################")
                         LOG.info("DONE: No ads to delete found.")
                         LOG.info("############################################")
+                case "extend":
+                    self.configure_file_logging()
+                    self.load_config()
+                    # Check for updates on startup
+                    checker = UpdateChecker(self.config)
+                    checker.check_for_updates()
+
+                    # Default to all ads if no selector provided
+                    if not re.compile(r"\d+[,\d+]*").search(self.ads_selector):
+                        LOG.info(_("Extending all ads within 8-day window..."))
+                        self.ads_selector = "all"
+
+                    if ads := self.load_ads():
+                        await self.create_browser_session()
+                        await self.login()
+                        await self.extend_ads(ads)
+                    else:
+                        LOG.info("############################################")
+                        LOG.info("DONE: No ads found to extend.")
+                        LOG.info("############################################")
                 case "download":
                     self.configure_file_logging()
                     # ad IDs depends on selector
@@ -346,6 +367,7 @@ class KleinanzeigenBot(WebScrapingMixin):
               verify   - Überprüft die Konfigurationsdateien
               delete   - Löscht Anzeigen
               update   - Aktualisiert bestehende Anzeigen
+              extend   - Verlängert Anzeigen innerhalb des 8-Tage-Zeitfensters
               download - Lädt eine oder mehrere Anzeigen herunter
               update-check - Prüft auf verfügbare Updates
               update-content-hash - Berechnet den content_hash aller Anzeigen anhand der aktuellen ad_defaults neu;
@@ -376,6 +398,9 @@ class KleinanzeigenBot(WebScrapingMixin):
                     Mögliche Werte:
                     * changed: Aktualisiert nur Anzeigen, die seit der letzten Veröffentlichung geändert wurden
                     * <id(s)>: Gibt eine oder mehrere Anzeigen-IDs zum Aktualisieren an, z. B. "--ads=1,2,3"
+              --ads=<id(s)> (extend) - Gibt an, welche Anzeigen verlängert werden sollen
+                    Standardmäßig werden alle Anzeigen verlängert, die innerhalb von 8 Tagen ablaufen.
+                    Mit dieser Option können Sie bestimmte Anzeigen-IDs angeben, z. B. "--ads=1,2,3"
               --force           - Alias für '--ads=all'
               --keep-old        - Verhindert das Löschen alter Anzeigen bei erneuter Veröffentlichung
               --config=<PATH>   - Pfad zur YAML- oder JSON-Konfigurationsdatei (STANDARD: ./config.yaml)
@@ -392,6 +417,7 @@ class KleinanzeigenBot(WebScrapingMixin):
               verify   - verifies the configuration files
               delete   - deletes ads
               update   - updates published ads
+              extend   - extends ads within the 8-day window before expiry
               download - downloads one or multiple ads
               update-check - checks for available updates
               update-content-hash – recalculates each ad's content_hash based on the current ad_defaults;
@@ -420,6 +446,9 @@ class KleinanzeigenBot(WebScrapingMixin):
                     Possible values:
                     * changed: only update ads that have been modified since last publication
                     * <id(s)>: provide one or several ads by ID to update, like e.g. "--ads=1,2,3"
+              --ads=<id(s)> (extend) - specifies which ads to extend
+                    By default, extends all ads expiring within 8 days.
+                    Use this option to specify ad IDs, e.g. "--ads=1,2,3"
               --force           - alias for '--ads=all'
               --keep-old        - don't delete old ads on republication
               --config=<PATH>   - path to the config YAML or JSON file (DEFAULT: ./config.yaml)
@@ -879,6 +908,113 @@ class KleinanzeigenBot(WebScrapingMixin):
         ad_cfg.id = None
         return True
 
+    async def extend_ads(self, ad_cfgs:list[tuple[str, Ad, dict[str, Any]]]) -> None:
+        """Extends ads that are close to expiry."""
+        # Fetch currently published ads from API
+        published_ads = json.loads(
+            (await self.web_request(f"{self.root_url}/m-meine-anzeigen-verwalten.json?sort=DEFAULT"))["content"])["ads"]
+
+        # Filter ads that need extension
+        ads_to_extend = []
+        for (ad_file, ad_cfg, ad_cfg_orig) in ad_cfgs:
+            # Skip unpublished ads (no ID)
+            if not ad_cfg.id:
+                LOG.info(_(" -> SKIPPED: ad '%s' is not published yet"), ad_cfg.title)
+                continue
+
+            # Find ad in published list
+            published_ad = next((ad for ad in published_ads if ad["id"] == ad_cfg.id), None)
+            if not published_ad:
+                LOG.warning(_(" -> SKIPPED: ad '%s' (ID: %s) not found in published ads"), ad_cfg.title, ad_cfg.id)
+                continue
+
+            # Skip non-active ads
+            if published_ad.get("state") != "active":
+                LOG.info(_(" -> SKIPPED: ad '%s' is not active (state: %s)"), ad_cfg.title, published_ad.get("state"))
+                continue
+
+            # Check if ad is within 8-day extension window using API's endDate
+            end_date_str = published_ad.get("endDate")
+            if not end_date_str:
+                LOG.warning(_(" -> SKIPPED: ad '%s' has no endDate in API response"), ad_cfg.title)
+                continue
+
+            # Intentionally parsing naive datetime from kleinanzeigen API's German date format, timezone not relevant for date-only comparison
+            end_date = datetime.strptime(end_date_str, "%d.%m.%Y")  # noqa: DTZ007
+            days_until_expiry = (end_date.date() - misc.now().date()).days
+
+            # Magic value 8 is kleinanzeigen.de's platform policy: extensions only possible within 8 days of expiry
+            if days_until_expiry <= 8:  # noqa: PLR2004
+                LOG.info(_(" -> ad '%s' expires in %d days, will extend"), ad_cfg.title, days_until_expiry)
+                ads_to_extend.append((ad_file, ad_cfg, ad_cfg_orig, published_ad))
+            else:
+                LOG.info(_(" -> SKIPPED: ad '%s' expires in %d days (can only extend within 8 days)"),
+                        ad_cfg.title, days_until_expiry)
+
+        if not ads_to_extend:
+            LOG.info(_("No ads need extension at this time."))
+            LOG.info("############################################")
+            LOG.info(_("DONE: No ads extended."))
+            LOG.info("############################################")
+            return
+
+        # Process extensions
+        success_count = 0
+        for idx, (ad_file, ad_cfg, ad_cfg_orig, _published_ad) in enumerate(ads_to_extend, start = 1):
+            LOG.info(_("Processing %s/%s: '%s' from [%s]..."), idx, len(ads_to_extend), ad_cfg.title, ad_file)
+            if await self.extend_ad(ad_file, ad_cfg, ad_cfg_orig):
+                success_count += 1
+            await self.web_sleep()
+
+        LOG.info("############################################")
+        LOG.info(_("DONE: Extended %s"), pluralize("ad", success_count))
+        LOG.info("############################################")
+
+    async def extend_ad(self, ad_file:str, ad_cfg:Ad, ad_cfg_orig:dict[str, Any]) -> bool:
+        """Extends a single ad listing."""
+        LOG.info(_("Extending ad '%s' (ID: %s)..."), ad_cfg.title, ad_cfg.id)
+
+        try:
+            # Navigate to ad management page
+            await self.web_open(f"{self.root_url}/m-meine-anzeigen.html")
+
+            # Find and click "Verlängern" (extend) button for this ad
+            extend_button_xpath = f'//li[@data-adid="{ad_cfg.id}"]//button[contains(., "Verlängern")]'
+
+            try:
+                await self.web_click(By.XPATH, extend_button_xpath)
+            except TimeoutError:
+                LOG.error(_(" -> FAILED: Could not find extend button for ad ID %s"), ad_cfg.id)
+                return False
+
+            # Handle confirmation dialog
+            # After clicking "Verlängern", a dialog appears with:
+            # - Title: "Vielen Dank!"
+            # - Message: "Deine Anzeige ... wurde erfolgreich verlängert."
+            # - Paid bump-up option (skipped by closing dialog)
+            # Simply close the dialog with the X button (aria-label="Schließen")
+            try:
+                dialog_close_timeout = self._timeout("quick_dom")
+                await self.web_click(By.CSS_SELECTOR, 'button[aria-label="Schließen"]', timeout = dialog_close_timeout)
+                LOG.debug(" -> Closed confirmation dialog")
+            except TimeoutError:
+                LOG.warning(_(" -> No confirmation dialog found, extension may have completed directly"))
+
+            # Update metadata in YAML file
+            # Update updated_on to track when ad was extended
+            ad_cfg_orig["updated_on"] = misc.now().isoformat(timespec = "seconds")
+            dicts.save_dict(ad_file, ad_cfg_orig)
+
+            LOG.info(_(" -> SUCCESS: ad extended with ID %s"), ad_cfg.id)
+            return True
+
+        except TimeoutError as ex:
+            LOG.error(_(" -> FAILED: Timeout while extending ad '%s': %s"), ad_cfg.title, ex)
+            return False
+        except OSError as ex:
+            LOG.error(_(" -> FAILED: Could not persist extension for ad '%s': %s"), ad_cfg.title, ex)
+            return False
+
     async def __check_publishing_result(self) -> bool:
         # Check for success messages
         return await self.web_check(By.ID, "checking-done", Is.DISPLAYED) or await self.web_check(By.ID, "not-completed", Is.DISPLAYED)
diff --git a/src/kleinanzeigen_bot/resources/translations.de.yaml b/src/kleinanzeigen_bot/resources/translations.de.yaml
index 8497808..6358085 100644
--- a/src/kleinanzeigen_bot/resources/translations.de.yaml
+++ b/src/kleinanzeigen_bot/resources/translations.de.yaml
@@ -91,6 +91,27 @@ kleinanzeigen_bot/__init__.py:
     "Expected CSRF Token not found in HTML content!": "Erwartetes CSRF-Token wurde im HTML-Inhalt nicht gefunden!"
     " -> deleting %s '%s'...": " -> lösche %s '%s'..."
 
+  extend_ads:
+    "No ads need extension at this time.": "Keine Anzeigen müssen derzeit verlängert werden."
+    "DONE: No ads extended.": "FERTIG: Keine Anzeigen verlängert."
+    "DONE: Extended %s": "FERTIG: %s verlängert"
+    "ad": "Anzeige"
+    " -> SKIPPED: ad '%s' is not published yet": " -> ÜBERSPRUNGEN: Anzeige '%s' ist noch nicht veröffentlicht"
+    " -> SKIPPED: ad '%s' (ID: %s) not found in published ads": " -> ÜBERSPRUNGEN: Anzeige '%s' (ID: %s) nicht gefunden"
+    " -> SKIPPED: ad '%s' is not active (state: %s)": " -> ÜBERSPRUNGEN: Anzeige '%s' ist nicht aktiv (Status: %s)"
+    " -> SKIPPED: ad '%s' has no endDate in API response": " -> ÜBERSPRUNGEN: Anzeige '%s' hat kein Ablaufdatum in API-Antwort"
+    " -> ad '%s' expires in %d days, will extend": " -> Anzeige '%s' läuft in %d Tagen ab, wird verlängert"
+    " -> SKIPPED: ad '%s' expires in %d days (can only extend within 8 days)": " -> ÜBERSPRUNGEN: Anzeige '%s' läuft in %d Tagen ab (Verlängern nur innerhalb von 8 Tagen möglich)"
+    "Processing %s/%s: '%s' from [%s]...": "Verarbeite %s/%s: '%s' aus [%s]..."
+
+  extend_ad:
+    "Extending ad '%s' (ID: %s)...": "Verlängere Anzeige '%s' (ID: %s)..."
+    " -> FAILED: Could not find extend button for ad ID %s": " -> FEHLER: 'Verlängern'-Button für Anzeigen-ID %s nicht gefunden"
+    " -> No confirmation dialog found, extension may have completed directly": " -> Kein Bestätigungsdialog gefunden"
+    " -> SUCCESS: ad extended with ID %s": " -> ERFOLG: Anzeige mit ID %s verlängert"
+    " -> FAILED: Timeout while extending ad '%s': %s": " -> FEHLER: Zeitüberschreitung beim Verlängern der Anzeige '%s': %s"
+    " -> FAILED: Could not persist extension for ad '%s': %s": " -> FEHLER: Verlängerung der Anzeige '%s' konnte nicht gespeichert werden: %s"
+
   publish_ads:
     "Processing %s/%s: '%s' from [%s]...": "Verarbeite %s/%s: '%s' von [%s]..."
     "Skipping because ad is reserved": "Überspringen, da Anzeige reserviert ist"
@@ -183,6 +204,8 @@ kleinanzeigen_bot/__init__.py:
     "DONE: No new/outdated ads found.": "FERTIG: Keine neuen/veralteten Anzeigen gefunden."
     "DONE: No ads to delete found.": "FERTIG: Keine zu löschenden Anzeigen gefunden."
     "DONE: No changed ads found.": "FERTIG: Keine geänderten Anzeigen gefunden."
+    "Extending all ads within 8-day window...": "Verlängere alle Anzeigen innerhalb des 8-Tage-Zeitfensters..."
+    "DONE: No ads found to extend.": "FERTIG: Keine Anzeigen zum Verlängern gefunden."
     "You provided no ads selector. Defaulting to \"new\".": "Es wurden keine Anzeigen-Selektor angegeben. Es wird \"new\" verwendet."
     "You provided no ads selector. Defaulting to \"changed\".": "Es wurden keine Anzeigen-Selektor angegeben. Es wird \"changed\" verwendet."
     "Unknown command: %s": "Unbekannter Befehl: %s"
diff --git a/tests/unit/test_extend_command.py b/tests/unit/test_extend_command.py
new file mode 100644
index 0000000..6e4e1be
--- /dev/null
+++ b/tests/unit/test_extend_command.py
@@ -0,0 +1,568 @@
+# SPDX-FileCopyrightText: © Jens Bergmann and contributors
+# SPDX-License-Identifier: AGPL-3.0-or-later
+# SPDX-ArtifactOfProjectHomePage: https://github.com/Second-Hand-Friends/kleinanzeigen-bot/
+import json  # isort: skip
+from datetime import datetime, timedelta
+from pathlib import Path
+from typing import Any
+from unittest.mock import AsyncMock, patch
+
+import pytest
+
+from kleinanzeigen_bot import KleinanzeigenBot, misc
+from kleinanzeigen_bot.model.ad_model import Ad
+from kleinanzeigen_bot.utils import dicts
+
+
+@pytest.fixture
+def base_ad_config_with_id() -> dict[str, Any]:
+    """Provide a base ad configuration with an ID for extend tests."""
+    return {
+        "id": 12345,
+        "title": "Test Ad Title",
+        "description": "Test Description",
+        "type": "OFFER",
+        "price_type": "FIXED",
+        "price": 100,
+        "shipping_type": "SHIPPING",
+        "shipping_options": [],
+        "category": "160",
+        "special_attributes": {},
+        "sell_directly": False,
+        "images": [],
+        "active": True,
+        "republication_interval": 7,
+        "created_on": "2024-12-07T10:00:00",
+        "updated_on": "2024-12-10T15:20:00",
+        "contact": {
+            "name": "Test User",
+            "zipcode": "12345",
+            "location": "Test City",
+            "street": "",
+            "phone": ""
+        }
+    }
+
+
+class TestExtendCommand:
+    """Tests for the extend command functionality."""
+
+    @pytest.mark.asyncio
+    async def test_run_extend_command_no_ads(self, test_bot:KleinanzeigenBot) -> None:
+        """Test running extend command with no ads."""
+        with patch.object(test_bot, "load_config"), \
+                patch.object(test_bot, "load_ads", return_value = []), \
+                patch("kleinanzeigen_bot.UpdateChecker"):
+            await test_bot.run(["script.py", "extend"])
+            assert test_bot.command == "extend"
+            assert test_bot.ads_selector == "all"
+
+    @pytest.mark.asyncio
+    async def test_run_extend_command_with_specific_ids(self, test_bot:KleinanzeigenBot) -> None:
+        """Test running extend command with specific ad IDs."""
+        with patch.object(test_bot, "load_config"), \
+                patch.object(test_bot, "load_ads", return_value = []), \
+                patch.object(test_bot, "create_browser_session", new_callable = AsyncMock), \
+                patch.object(test_bot, "login", new_callable = AsyncMock), \
+                patch("kleinanzeigen_bot.UpdateChecker"):
+            await test_bot.run(["script.py", "extend", "--ads=12345,67890"])
+            assert test_bot.command == "extend"
+            assert test_bot.ads_selector == "12345,67890"
+
+
+class TestExtendAdsMethod:
+    """Tests for the extend_ads() method."""
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_skips_unpublished_ad(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that extend_ads skips ads without an ID (unpublished)."""
+        # Create ad without ID
+        ad_config = base_ad_config_with_id.copy()
+        ad_config["id"] = None
+        ad_cfg = Ad.model_validate(ad_config)
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock):
+            mock_request.return_value = {"content": '{"ads": []}'}
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, ad_config)])
+
+            # Verify no extension was attempted
+            mock_request.assert_called_once()  # Only the API call to get published ads
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_skips_ad_not_in_published_list(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that extend_ads skips ads not found in the published ads API response."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock):
+            # Return empty published ads list
+            mock_request.return_value = {"content": '{"ads": []}'}
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify no extension was attempted
+            mock_request.assert_called_once()
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_skips_inactive_ad(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that extend_ads skips ads with state != 'active'."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "paused",  # Not active
+                    "endDate": "05.02.2026"
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad:
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify extend_ad was not called
+            mock_extend_ad.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_skips_ad_without_enddate(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that extend_ads skips ads without endDate in API response."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "active"
+                    # No endDate field
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad:
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify extend_ad was not called
+            mock_extend_ad.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_skips_ad_outside_window(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that extend_ads skips ads expiring more than 8 days in the future."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Set end date to 30 days from now (outside 8-day window)
+        future_date = misc.now() + timedelta(days = 30)
+        end_date_str = future_date.strftime("%d.%m.%Y")
+
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "active",
+                    "endDate": end_date_str
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad:
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify extend_ad was not called
+            mock_extend_ad.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_extends_ad_within_window(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that extend_ads extends ads within the 8-day window."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Set end date to 5 days from now (within 8-day window)
+        future_date = misc.now() + timedelta(days = 5)
+        end_date_str = future_date.strftime("%d.%m.%Y")
+
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "active",
+                    "endDate": end_date_str
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad:
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+            mock_extend_ad.return_value = True
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify extend_ad was called
+            mock_extend_ad.assert_called_once()
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_no_eligible_ads(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test extend_ads when no ads are eligible for extension."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Set end date to 30 days from now (outside window)
+        future_date = misc.now() + timedelta(days = 30)
+        end_date_str = future_date.strftime("%d.%m.%Y")
+
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "active",
+                    "endDate": end_date_str
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad:
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify extend_ad was not called
+            mock_extend_ad.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_handles_multiple_ads(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that extend_ads processes multiple ads correctly."""
+        ad_cfg1 = Ad.model_validate(base_ad_config_with_id)
+
+        # Create second ad
+        ad_config2 = base_ad_config_with_id.copy()
+        ad_config2["id"] = 67890
+        ad_config2["title"] = "Second Test Ad"
+        ad_cfg2 = Ad.model_validate(ad_config2)
+
+        # Set end dates - one within window, one outside
+        within_window = misc.now() + timedelta(days = 5)
+        outside_window = misc.now() + timedelta(days = 30)
+
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "active",
+                    "endDate": within_window.strftime("%d.%m.%Y")
+                },
+                {
+                    "id": 67890,
+                    "title": "Second Test Ad",
+                    "state": "active",
+                    "endDate": outside_window.strftime("%d.%m.%Y")
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad:
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+            mock_extend_ad.return_value = True
+
+            await test_bot.extend_ads([
+                ("test1.yaml", ad_cfg1, base_ad_config_with_id),
+                ("test2.yaml", ad_cfg2, ad_config2)
+            ])
+
+            # Verify extend_ad was called only once (for the ad within window)
+            assert mock_extend_ad.call_count == 1
+
+
+class TestExtendAdMethod:
+    """Tests for the extend_ad() method."""
+
+    @pytest.mark.asyncio
+    async def test_extend_ad_success(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any],
+        tmp_path:Path
+    ) -> None:
+        """Test successful ad extension."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Create temporary YAML file
+        ad_file = tmp_path / "test_ad.yaml"
+        dicts.save_dict(str(ad_file), base_ad_config_with_id)
+
+        with patch.object(test_bot, "web_open", new_callable = AsyncMock), \
+                patch.object(test_bot, "web_click", new_callable = AsyncMock), \
+                patch("kleinanzeigen_bot.misc.now") as mock_now:
+            # Test mock datetime - timezone not relevant for timestamp formatting test
+            mock_now.return_value = datetime(2025, 1, 28, 14, 30, 0)  # noqa: DTZ001
+
+            result = await test_bot.extend_ad(str(ad_file), ad_cfg, base_ad_config_with_id)
+
+            assert result is True
+
+            # Verify updated_on was updated in the YAML file
+            updated_config = dicts.load_dict(str(ad_file))
+            assert updated_config["updated_on"] == "2025-01-28T14:30:00"
+
+    @pytest.mark.asyncio
+    async def test_extend_ad_button_not_found(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any],
+        tmp_path:Path
+    ) -> None:
+        """Test extend_ad when the Verlängern button is not found."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Create temporary YAML file
+        ad_file = tmp_path / "test_ad.yaml"
+        dicts.save_dict(str(ad_file), base_ad_config_with_id)
+
+        with patch.object(test_bot, "web_open", new_callable = AsyncMock), \
+                patch.object(test_bot, "web_click", new_callable = AsyncMock) as mock_click:
+            # Simulate button not found by raising TimeoutError
+            mock_click.side_effect = TimeoutError("Button not found")
+
+            result = await test_bot.extend_ad(str(ad_file), ad_cfg, base_ad_config_with_id)
+
+            assert result is False
+
+    @pytest.mark.asyncio
+    async def test_extend_ad_dialog_timeout(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any],
+        tmp_path:Path
+    ) -> None:
+        """Test extend_ad when the confirmation dialog times out (no dialog appears)."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Create temporary YAML file
+        ad_file = tmp_path / "test_ad.yaml"
+        dicts.save_dict(str(ad_file), base_ad_config_with_id)
+
+        with patch.object(test_bot, "web_open", new_callable = AsyncMock), \
+                patch.object(test_bot, "web_click", new_callable = AsyncMock) as mock_click, \
+                patch("kleinanzeigen_bot.misc.now") as mock_now:
+            # Test mock datetime - timezone not relevant for timestamp formatting test
+            mock_now.return_value = datetime(2025, 1, 28, 14, 30, 0)  # noqa: DTZ001
+
+            # First click (Verlängern button) succeeds, second click (dialog close) times out
+            mock_click.side_effect = [None, TimeoutError("Dialog not found")]
+
+            result = await test_bot.extend_ad(str(ad_file), ad_cfg, base_ad_config_with_id)
+
+            # Should still succeed (dialog might not appear)
+            assert result is True
+
+    @pytest.mark.asyncio
+    async def test_extend_ad_exception_handling(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any],
+        tmp_path:Path
+    ) -> None:
+        """Test extend_ad propagates unexpected exceptions."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Create temporary YAML file
+        ad_file = tmp_path / "test_ad.yaml"
+        dicts.save_dict(str(ad_file), base_ad_config_with_id)
+
+        with patch.object(test_bot, "web_open", new_callable = AsyncMock) as mock_open:
+            # Simulate unexpected exception
+            mock_open.side_effect = Exception("Unexpected error")
+
+            with pytest.raises(Exception, match = "Unexpected error"):
+                await test_bot.extend_ad(str(ad_file), ad_cfg, base_ad_config_with_id)
+
+    @pytest.mark.asyncio
+    async def test_extend_ad_updates_yaml_file(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any],
+        tmp_path:Path
+    ) -> None:
+        """Test that extend_ad correctly updates the YAML file with new timestamp."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Create temporary YAML file
+        ad_file = tmp_path / "test_ad.yaml"
+        original_updated_on = base_ad_config_with_id["updated_on"]
+        dicts.save_dict(str(ad_file), base_ad_config_with_id)
+
+        with patch.object(test_bot, "web_open", new_callable = AsyncMock), \
+                patch.object(test_bot, "web_click", new_callable = AsyncMock), \
+                patch("kleinanzeigen_bot.misc.now") as mock_now:
+            # Test mock datetime - timezone not relevant for timestamp formatting test
+            mock_now.return_value = datetime(2025, 1, 28, 14, 30, 0)  # noqa: DTZ001
+
+            await test_bot.extend_ad(str(ad_file), ad_cfg, base_ad_config_with_id)
+
+            # Load the updated file and verify the timestamp changed
+            updated_config = dicts.load_dict(str(ad_file))
+            assert updated_config["updated_on"] != original_updated_on
+            assert updated_config["updated_on"] == "2025-01-28T14:30:00"
+
+
+class TestExtendEdgeCases:
+    """Tests for edge cases and boundary conditions."""
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_exactly_8_days(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that ads expiring exactly in 8 days are eligible for extension."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Set end date to exactly 8 days from now (boundary case)
+        future_date = misc.now() + timedelta(days = 8)
+        end_date_str = future_date.strftime("%d.%m.%Y")
+
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "active",
+                    "endDate": end_date_str
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad:
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+            mock_extend_ad.return_value = True
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify extend_ad was called (8 days is within the window)
+            mock_extend_ad.assert_called_once()
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_exactly_9_days(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that ads expiring in exactly 9 days are not eligible for extension."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Set end date to exactly 9 days from now (just outside window)
+        future_date = misc.now() + timedelta(days = 9)
+        end_date_str = future_date.strftime("%d.%m.%Y")
+
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "active",
+                    "endDate": end_date_str
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad:
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify extend_ad was not called (9 days is outside the window)
+            mock_extend_ad.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_extend_ads_date_parsing_german_format(
+        self,
+        test_bot:KleinanzeigenBot,
+        base_ad_config_with_id:dict[str, Any]
+    ) -> None:
+        """Test that extend_ads correctly parses German date format (DD.MM.YYYY)."""
+        ad_cfg = Ad.model_validate(base_ad_config_with_id)
+
+        # Use a specific German date format
+        published_ads_json = {
+            "ads": [
+                {
+                    "id": 12345,
+                    "title": "Test Ad Title",
+                    "state": "active",
+                    "endDate": "05.02.2026"  # German format: DD.MM.YYYY
+                }
+            ]
+        }
+
+        with patch.object(test_bot, "web_request", new_callable = AsyncMock) as mock_request, \
+                patch.object(test_bot, "web_sleep", new_callable = AsyncMock), \
+                patch.object(test_bot, "extend_ad", new_callable = AsyncMock) as mock_extend_ad, \
+                patch("kleinanzeigen_bot.misc.now") as mock_now:
+            # Mock now() to return a date where 05.02.2026 would be within 8 days
+            # Test mock datetime - timezone not relevant for date comparison test
+            mock_now.return_value = datetime(2026, 1, 28)  # noqa: DTZ001
+            mock_request.return_value = {"content": json.dumps(published_ads_json)}
+            mock_extend_ad.return_value = True
+
+            await test_bot.extend_ads([("test.yaml", ad_cfg, base_ad_config_with_id)])
+
+            # Verify extend_ad was called (date was parsed correctly)
+            mock_extend_ad.assert_called_once()