diff --git a/Classes/Utility/TagUtility.php b/Classes/Utility/TagUtility.php
index 4c14dce..a73764b 100644
--- a/Classes/Utility/TagUtility.php
+++ b/Classes/Utility/TagUtility.php
@@ -4,6 +4,7 @@
 
 namespace Zeroseven\Pagebased\Utility;
 
+use TYPO3\CMS\Core\Configuration\Features;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 use TYPO3\CMS\Extbase\Persistence\QueryResultInterface;
 use Zeroseven\Pagebased\Domain\Model\Demand\ObjectDemandInterface;
@@ -53,6 +54,45 @@ public static function collectTagsFromStrings(array $tagStrings): array
 
     public static function getTags(ObjectDemandInterface $demand, RepositoryInterface $repository, bool $ignoreTagsFromDemand = null, int $languageUid = null): ?array
     {
+        // When the nonglobal-tags feature is enabled, scope tags to the current rootline category.
+        if (GeneralUtility::makeInstance(Features::class)->isFeatureEnabled('pagebased.nonglobalTags')) {
+            if (!$demand->{'getCategory'}()) {
+                // Resolve the category doktype for this specific repository to avoid matching
+                // category pages from a different registration in multi-registration installations.
+                $registrationDoktype = RegistrationService::getRegistrationByRepository($repository)
+                    ?->getCategory()
+                    ?->getDocumentType();
+
+                $currentPage = RootLineUtility::getCurrentPage();
+                $pagesAbove = RootLineUtility::collectPagesAbove($currentPage, true);
+
+                // Find the first category page in the rootline that belongs to this registration.
+                // Fall back to any registered category doktype when the registration cannot be resolved.
+                $categoryUid = null;
+                foreach ($pagesAbove as $page) {
+                    if (!isset($page['doktype'])) {
+                        continue;
+                    }
+                    $doktype = (int)$page['doktype'];
+                    $matches = $registrationDoktype !== null
+                        ? $doktype === $registrationDoktype
+                        : RegistrationService::getRegistrationByCategoryDocumentType($doktype) !== null;
+
+                    if ($matches) {
+                        $categoryUid = (int)$page['uid'];
+                        break;
+                    }
+                }
+
+                if ($categoryUid) {
+                    $demand->{'setCategory'}($categoryUid);
+                } else {
+                    // No category found in rootline → return null to avoid showing all tags
+                    return null;
+                }
+            }
+        }
+
         // Override language
         if ($languageUid !== null) {
             $querySettings = $repository->getDefaultQuerySettings();
diff --git a/Tests/Functional/Fixtures/Database/pages_tags.csv b/Tests/Functional/Fixtures/Database/pages_tags.csv
new file mode 100644
index 0000000..c8a5b7e
--- /dev/null
+++ b/Tests/Functional/Fixtures/Database/pages_tags.csv
@@ -0,0 +1,9 @@
+pages,,,,,,,,,,,,,,,
+,uid,pid,title,doktype,sorting,deleted,hidden,nav_hide,sys_language_uid,l10n_parent,_pagebased_registration,_pagebased_site,_pagebased_child_object,pagebased_tags
+,1,0,Site Root,1,256,0,0,0,0,0,,1,0,
+,10,1,Category A,199,128,0,0,0,0,0,,1,0,
+,20,10,Object A1,1,128,0,0,0,0,0,test_news,1,0,"php,typo3"
+,21,10,Object A2,1,256,0,0,0,0,0,test_news,1,0,"php,symfony"
+,30,1,Category B,199,256,0,0,0,0,0,,1,0,
+,31,30,Object B1,1,128,0,0,0,0,0,test_news,1,0,"javascript,typo3"
+,40,1,Standalone Page,1,384,0,0,0,0,0,,1,0,
diff --git a/Tests/Functional/Utility/TagUtilityTest.php b/Tests/Functional/Utility/TagUtilityTest.php
new file mode 100644
index 0000000..7479455
--- /dev/null
+++ b/Tests/Functional/Utility/TagUtilityTest.php
@@ -0,0 +1,188 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Zeroseven\Pagebased\Tests\Functional\Utility;
+
+use TYPO3\TestingFramework\Core\Functional\FunctionalTestCase;
+use Zeroseven\Pagebased\Registration\CategoryRegistration;
+use Zeroseven\Pagebased\Registration\ObjectRegistration;
+use Zeroseven\Pagebased\Registration\Registration;
+use Zeroseven\Pagebased\Registration\RegistrationService;
+use Zeroseven\Pagebased\Tests\Functional\Fixtures\Classes\TestCategory;
+use Zeroseven\Pagebased\Tests\Functional\Fixtures\Classes\TestCategoryRepository;
+use Zeroseven\Pagebased\Tests\Functional\Fixtures\Classes\TestObject;
+use Zeroseven\Pagebased\Tests\Functional\Fixtures\Classes\TestObjectRepository;
+use Zeroseven\Pagebased\Utility\RootLineUtility;
+use Zeroseven\Pagebased\Utility\TagUtility;
+
+/**
+ * Functional tests for TagUtility::getTags() with the pagebased.nonglobalTags feature flag.
+ *
+ * Fixture layout (pages_tags.csv):
+ *   uid  1  → Site root (doktype=1)
+ *   uid 10  → Category A (doktype=199)
+ *   uid 20  → Object in Category A, tags: "php,typo3"
+ *   uid 21  → Object in Category A, tags: "php,symfony"
+ *   uid 30  → Category B (doktype=199)
+ *   uid 31  → Object in Category B, tags: "javascript,typo3"
+ *   uid 40  → Standalone page (doktype=1, no registered category in rootline)
+ *
+ * Feature flag OFF (default): tags are collected globally across all categories.
+ * Feature flag ON:
+ *   - Category already set in demand → rootline detection is skipped.
+ *   - No category in demand, category page found in rootline → demand is scoped automatically.
+ *   - No category in demand, no category page in rootline → null returned.
+ */
+class TagUtilityTest extends FunctionalTestCase
+{
+    protected array $testExtensionsToLoad = [
+        'typo3conf/ext/pagebased',
+    ];
+
+    protected array $coreExtensionsToLoad = [
+        'core',
+        'frontend',
+    ];
+
+    private TestObjectRepository $repository;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->bootstrapTestRegistration();
+        $this->importCSVDataSet(__DIR__ . '/../Fixtures/Database/pages_tags.csv');
+
+        $this->repository = $this->get(TestObjectRepository::class);
+
+        // Ensure the feature flag is off by default for each test.
+        $GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['pagebased.nonglobalTags'] = false;
+    }
+
+    protected function tearDown(): void
+    {
+        // Clear the static RootLineUtility cache so page-context changes between
+        // tests do not bleed into one another.
+        // Note: setAccessible(true) is intentionally omitted – it is a no-op since PHP 8.1
+        // and produces a deprecation notice on PHP 8.4.
+        $reflection = new \ReflectionProperty(RootLineUtility::class, 'cache');
+        $reflection->setValue(null, []);
+
+        unset($_GET['id']);
+        $GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['pagebased.nonglobalTags'] = false;
+
+        parent::tearDown();
+    }
+
+    private function bootstrapTestRegistration(): void
+    {
+        $objectRegistration = new ObjectRegistration('Test Object');
+        $objectRegistration->setClassName(TestObject::class);
+        $objectRegistration->setRepositoryClass(TestObjectRepository::class);
+
+        $categoryRegistration = new CategoryRegistration('Test Category');
+        $categoryRegistration->setClassName(TestCategory::class);
+        $categoryRegistration->setRepositoryClass(TestCategoryRepository::class);
+        $categoryRegistration->setDocumentType(199);
+
+        $registration = new Registration('test', 'test_news');
+        $registration->setObject($objectRegistration);
+        $registration->setCategory($categoryRegistration);
+
+        RegistrationService::addRegistration($registration);
+    }
+
+    // ---------------------------------------------------------------------------
+    // Feature flag OFF (default behaviour)
+    // ---------------------------------------------------------------------------
+
+    /** @test */
+    public function getTagsReturnsGlobalTagsWhenFeatureFlagIsOff(): void
+    {
+        $GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['pagebased.nonglobalTags'] = false;
+
+        $demand = $this->repository->initializeDemand();
+        $tags = TagUtility::getTags($demand, $this->repository);
+
+        // All objects across all categories are included: php, typo3, symfony, javascript
+        self::assertNotNull($tags);
+        self::assertContains('php', $tags);
+        self::assertContains('typo3', $tags);
+        self::assertContains('symfony', $tags);
+        self::assertContains('javascript', $tags);
+        self::assertSame(['javascript', 'php', 'symfony', 'typo3'], $tags);
+    }
+
+    // ---------------------------------------------------------------------------
+    // Feature flag ON – rootline detection active
+    // ---------------------------------------------------------------------------
+
+    /** @test */
+    public function getTagsScopesTagsToCategoryFoundInRootlineWhenFlagIsOn(): void
+    {
+        $GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['pagebased.nonglobalTags'] = true;
+
+        // Simulate browsing object page 20 (child of Category A, uid=10)
+        $_GET['id'] = '20';
+
+        $demand = $this->repository->initializeDemand();
+        $tags = TagUtility::getTags($demand, $this->repository);
+
+        // Only objects in Category A (uid 20, 21): php, typo3, symfony
+        self::assertNotNull($tags);
+        self::assertSame(['php', 'symfony', 'typo3'], $tags);
+        self::assertNotContains('javascript', $tags);
+    }
+
+    /** @test */
+    public function getTagsReturnsNullWhenFlagIsOnButNoCategoryPageInRootline(): void
+    {
+        $GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['pagebased.nonglobalTags'] = true;
+
+        // Simulate browsing a standalone page (uid=40) with no registered category ancestor
+        $_GET['id'] = '40';
+
+        $demand = $this->repository->initializeDemand();
+        $result = TagUtility::getTags($demand, $this->repository);
+
+        self::assertNull($result);
+    }
+
+    /** @test */
+    public function getTagsSkipsRootlineDetectionWhenCategoryAlreadySetInDemand(): void
+    {
+        $GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['pagebased.nonglobalTags'] = true;
+
+        // Category B (uid=30) is set explicitly – rootline should not be consulted.
+        // $_GET['id'] points to a page outside any category to prove rootline is skipped.
+        $_GET['id'] = '40';
+
+        $demand = $this->repository->initializeDemand();
+        $demand->{'setCategory'}(30);
+
+        $tags = TagUtility::getTags($demand, $this->repository);
+
+        // Only objects in Category B (uid 31): javascript, typo3
+        self::assertNotNull($tags);
+        self::assertSame(['javascript', 'typo3'], $tags);
+        self::assertNotContains('php', $tags);
+        self::assertNotContains('symfony', $tags);
+    }
+
+    /** @test */
+    public function getTagsOnCategoryPageItselfResolvesCorrectlyWhenFlagIsOn(): void
+    {
+        $GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['pagebased.nonglobalTags'] = true;
+
+        // Simulate browsing the Category A page itself (uid=10, doktype=199)
+        $_GET['id'] = '10';
+
+        $demand = $this->repository->initializeDemand();
+        $tags = TagUtility::getTags($demand, $this->repository);
+
+        // collectPagesAbove with includingStartingPoint=true includes uid=10 itself
+        self::assertNotNull($tags);
+        self::assertSame(['php', 'symfony', 'typo3'], $tags);
+    }
+}
diff --git a/ext_localconf.php b/ext_localconf.php
index 9149894..484c53e 100644
--- a/ext_localconf.php
+++ b/ext_localconf.php
@@ -7,6 +7,10 @@
 \Zeroseven\Pagebased\Hooks\IconFactory\OverrideIconOverlay::register();
 \Zeroseven\Pagebased\Middleware\RssFeed::registerCache();
 
+// Opt-in: scope tag queries to the blog category found in the current page's rootline.
+// Enable per installation in AdditionalConfiguration.php or via the Install Tool Features panel.
+$GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['pagebased.nonglobalTags'] ??= false;
+
 // Tag query result cache – stores distinct tag lists per registration/category/language.
 // TYPO3 clears this automatically when pages with matching tags are modified.
 $GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['pagebased_tags'] ??= [