diff --git a/libraries/ortbConverter/processors/default.js b/libraries/ortbConverter/processors/default.js
index b1fb5be77a5..001d0d808bf 100644
--- a/libraries/ortbConverter/processors/default.js
+++ b/libraries/ortbConverter/processors/default.js
@@ -111,6 +111,9 @@ export const DEFAULT_PROCESSORS = {
         if (bid.ext?.eventtrackers) {
           bidResponse.eventtrackers = (bidResponse.eventtrackers ?? []).concat(bid.ext.eventtrackers);
         }
+        if (bid.cattax) {
+          bidResponse.meta.cattax = bid.cattax;
+        }
       }
     }
   }
diff --git a/modules/bidResponseFilter/index.js b/modules/bidResponseFilter/index.js
index 64026958bc6..4f61c81722d 100644
--- a/modules/bidResponseFilter/index.js
+++ b/modules/bidResponseFilter/index.js
@@ -29,7 +29,7 @@ export function reset() {
 }
 
 export function addBidResponseHook(next, adUnitCode, bid, reject, index = auctionManager.index) {
-  const {bcat = [], badv = []} = index.getOrtb2(bid) || {};
+  const {bcat = [], badv = [], cattax = 1} = index.getOrtb2(bid) || {};
   const bidRequest = index.getBidRequest(bid);
   const battr = bidRequest?.ortb2Imp[bid.mediaType]?.battr || index.getAdUnit(bid)?.ortb2Imp[bid.mediaType]?.battr || [];
 
@@ -43,11 +43,13 @@ export function addBidResponseHook(next, adUnitCode, bid, reject, index = auctio
     advertiserDomains = [],
     attr: metaAttr,
     mediaType: metaMediaType,
+    cattax: metaCattax = 1,
   } = bid.meta || {};
 
   // checking if bid fulfills ortb2 fields rules
-  if ((catConfig.enforce && bcat.some(category => [primaryCatId, ...secondaryCatIds].includes(category))) ||
-    (catConfig.blockUnknown && !primaryCatId)) {
+  const isCattaxMatch = metaCattax === cattax;
+  if ((catConfig.enforce && isCattaxMatch && bcat.some(category => [primaryCatId, ...secondaryCatIds].includes(category))) ||
+    (catConfig.blockUnknown && (!isCattaxMatch || !primaryCatId))) {
     reject(BID_CATEGORY_REJECTION_REASON);
   } else if ((advConfig.enforce && badv.some(domain => advertiserDomains.includes(domain))) ||
     (advConfig.blockUnknown && !advertiserDomains.length)) {
diff --git a/test/spec/modules/bidResponseFilter_spec.js b/test/spec/modules/bidResponseFilter_spec.js
index c37003bde50..16acee9b87e 100644
--- a/test/spec/modules/bidResponseFilter_spec.js
+++ b/test/spec/modules/bidResponseFilter_spec.js
@@ -69,7 +69,8 @@ describe('bidResponseFilter', () => {
         advertiserDomains: ['domain1.com', 'domain2.com'],
         primaryCatId: 'EXAMPLE-CAT-ID',
         attr: 'attr',
-        mediaType: 'banner'
+        mediaType: 'banner',
+        cattax: 1
       }
     };
 
@@ -85,7 +86,8 @@ describe('bidResponseFilter', () => {
       meta: {
         advertiserDomains: ['domain1.com', 'domain2.com'],
         primaryCatId: 'BANNED_CAT1',
-        attr: 'attr'
+        attr: 'attr',
+        cattax: 1
       }
     };
     mockAuctionIndex.getOrtb2 = () => ({
@@ -96,6 +98,109 @@ describe('bidResponseFilter', () => {
     sinon.assert.calledWith(reject, BID_CATEGORY_REJECTION_REASON);
   });
 
+  describe('cattax (category taxonomy) match', () => {
+    it('should reject with BID_CATEGORY_REJECTION_REASON when cattax matches and primaryCatId is in bcat blocklist', () => {
+      const reject = sinon.stub();
+      const call = sinon.stub();
+      const bid = {
+        meta: {
+          advertiserDomains: ['domain1.com'],
+          primaryCatId: 'BANNED_CAT1',
+          attr: 1,
+          mediaType: 'banner',
+          cattax: 1
+        }
+      };
+      mockAuctionIndex.getOrtb2 = () => ({
+        badv: [], bcat: ['BANNED_CAT1'], cattax: 1
+      });
+      mockAuctionIndex.getBidRequest = () => ({
+        mediaTypes: { banner: {} },
+        ortb2Imp: {}
+      });
+
+      addBidResponseHook(call, 'adcode', bid, reject, mockAuctionIndex);
+      sinon.assert.calledWith(reject, BID_CATEGORY_REJECTION_REASON);
+      sinon.assert.notCalled(call);
+    });
+
+    it('should pass when cattax matches and primaryCatId is not in bcat blocklist', () => {
+      const reject = sinon.stub();
+      const call = sinon.stub();
+      const bid = {
+        meta: {
+          advertiserDomains: ['domain1.com'],
+          primaryCatId: 'ALLOWED_CAT',
+          attr: 1,
+          mediaType: 'banner',
+          cattax: 1
+        }
+      };
+      mockAuctionIndex.getOrtb2 = () => ({
+        badv: [], bcat: ['BANNED_CAT1'], cattax: 1
+      });
+      mockAuctionIndex.getBidRequest = () => ({
+        mediaTypes: { banner: {} },
+        ortb2Imp: {}
+      });
+
+      addBidResponseHook(call, 'adcode', bid, reject, mockAuctionIndex);
+      sinon.assert.notCalled(reject);
+      sinon.assert.calledOnce(call);
+    });
+
+    it('should reject with BID_CATEGORY_REJECTION_REASON when cattax does not match (treat primaryCatId as unknown)', () => {
+      const reject = sinon.stub();
+      const call = sinon.stub();
+      const bid = {
+        meta: {
+          advertiserDomains: ['domain1.com'],
+          primaryCatId: 'ALLOWED_CAT',
+          attr: 1,
+          mediaType: 'banner',
+          cattax: 2
+        }
+      };
+      mockAuctionIndex.getOrtb2 = () => ({
+        badv: [], bcat: ['BANNED_CAT1'], cattax: 1
+      });
+      mockAuctionIndex.getBidRequest = () => ({
+        mediaTypes: { banner: {} },
+        ortb2Imp: {}
+      });
+
+      addBidResponseHook(call, 'adcode', bid, reject, mockAuctionIndex);
+      sinon.assert.calledWith(reject, BID_CATEGORY_REJECTION_REASON);
+      sinon.assert.notCalled(call);
+    });
+
+    it('should pass when cattax does not match and blockUnknown is false (do not treat as unknown)', () => {
+      const reject = sinon.stub();
+      const call = sinon.stub();
+      const bid = {
+        meta: {
+          advertiserDomains: ['domain1.com'],
+          primaryCatId: 'BANNED_CAT1',
+          attr: 1,
+          mediaType: 'banner',
+          cattax: 2
+        }
+      };
+      mockAuctionIndex.getOrtb2 = () => ({
+        badv: [], bcat: ['BANNED_CAT1'], cattax: 1
+      });
+      mockAuctionIndex.getBidRequest = () => ({
+        mediaTypes: { banner: {} },
+        ortb2Imp: {}
+      });
+      config.setConfig({ [MODULE_NAME]: { cat: { blockUnknown: false } } });
+
+      addBidResponseHook(call, 'adcode', bid, reject, mockAuctionIndex);
+      sinon.assert.notCalled(reject);
+      sinon.assert.calledOnce(call);
+    });
+  });
+
   it('should reject the bid after failed ortb2 adv domains rule validation', () => {
     const rejection = sinon.stub();
     const call = sinon.stub();
@@ -103,7 +208,8 @@ describe('bidResponseFilter', () => {
       meta: {
         advertiserDomains: ['domain1.com', 'domain2.com'],
         primaryCatId: 'VALID_CAT',
-        attr: 'attr'
+        attr: 'attr',
+        cattax: 1
       }
     };
     mockAuctionIndex.getOrtb2 = () => ({
@@ -121,7 +227,8 @@ describe('bidResponseFilter', () => {
       meta: {
         advertiserDomains: ['validdomain1.com', 'validdomain2.com'],
         primaryCatId: 'VALID_CAT',
-        attr: 'BANNED_ATTR'
+        attr: 'BANNED_ATTR',
+        cattax: 1
       },
       mediaType: 'video'
     };
@@ -149,6 +256,7 @@ describe('bidResponseFilter', () => {
         primaryCatId: 'BANNED_CAT1',
         attr: 'valid_attr',
         mediaType: 'banner',
+        cattax: 1
       }
     };
 
@@ -177,7 +285,8 @@ describe('bidResponseFilter', () => {
         advertiserDomains: ['validdomain1.com', 'validdomain2.com'],
         primaryCatId: undefined,
         attr: 'valid_attr',
-        mediaType: 'banner'
+        mediaType: 'banner',
+        cattax: 1
       }
     };
 
@@ -207,7 +316,8 @@ describe('bidResponseFilter', () => {
         advertiserDomains: ['validdomain1.com', 'validdomain2.com'],
         primaryCatId: 'VALID_CAT',
         attr: 6,
-        mediaType: 'audio'
+        mediaType: 'audio',
+        cattax: 1
       },
     };