diff --git a/libraries/intentIqUtils/getCmpData.js b/libraries/intentIqUtils/getCmpData.js
index b23f0fbaffe..cdf5ecf0e73 100644
--- a/libraries/intentIqUtils/getCmpData.js
+++ b/libraries/intentIqUtils/getCmpData.js
@@ -1,4 +1,4 @@
-import { allConsent } from '../../src/consentHandler.js';
+import { allConsent } from "../../src/consentHandler.js";
 
 /**
  * Retrieves consent data from the Consent Management Platform (CMP).
@@ -12,8 +12,26 @@ export function getCmpData() {
 
   return {
     gdprApplies: consentData?.gdpr?.gdprApplies || false,
-    gdprString: typeof consentData?.gdpr?.consentString === 'string' ? consentData.gdpr.consentString : null,
-    uspString: typeof consentData?.usp === 'string' ? consentData.usp : null,
-    gppString: typeof consentData?.gpp?.gppString === 'string' ? consentData.gpp.gppString : null,
+    gdprString:
+      typeof consentData?.gdpr?.consentString === "string"
+        ? consentData.gdpr.consentString
+        : null,
+    uspString: typeof consentData?.usp === "string" ? consentData.usp : null,
+    gppString:
+      typeof consentData?.gpp?.gppString === "string"
+        ? consentData.gpp.gppString
+        : null,
   };
 }
+
+export function isValidValue(val) {
+  return !!val && val !== "undefined";
+}
+
+export function areCmpValuesEqual(a, b) {
+  const aValid = isValidValue(a);
+  const bValid = isValidValue(b);
+  if (!aValid && !bValid) return true;
+  if (aValid !== bValid) return false;
+  return a === b;
+}
diff --git a/modules/intentIqAnalyticsAdapter.js b/modules/intentIqAnalyticsAdapter.js
index 2838b8ea1d4..8b24105f85f 100644
--- a/modules/intentIqAnalyticsAdapter.js
+++ b/modules/intentIqAnalyticsAdapter.js
@@ -6,7 +6,7 @@ import { EVENTS } from '../src/constants.js';
 import { detectBrowser } from '../libraries/intentIqUtils/detectBrowserUtils.js';
 import { appendSPData } from '../libraries/intentIqUtils/urlUtils.js';
 import { appendVrrefAndFui, getCurrentUrl, getRelevantRefferer } from '../libraries/intentIqUtils/getRefferer.js';
-import { getCmpData } from '../libraries/intentIqUtils/getCmpData.js';
+import { getCmpData, areCmpValuesEqual, isValidValue } from '../libraries/intentIqUtils/getCmpData.js';
 import { getUnitPosition } from '../libraries/intentIqUtils/getUnitPosition.js';
 import {
   VERSION,
@@ -107,12 +107,23 @@ const iiqAnalyticsAnalyticsAdapter = Object.assign(adapter({ url: DEFAULT_URL, a
       case BID_WON:
         bidWon(args);
         break;
-      case BID_REQUESTED:
+      case BID_REQUESTED: {
         if (!alreadySubscribedOnGAM && shouldSubscribeOnGAM()) {
           alreadySubscribedOnGAM = true;
           gamPredictionReport(iiqConfig?.gamObjectReference, bidWon);
         }
+        const fpdFromGlobalObject = window[identityGlobalName]?.firstPartyData;
+        if (fpdFromGlobalObject) {
+          const currentCmpData = getCmpData();
+          const hasCmpMismatch = ['gdprString', 'gppString', 'uspString'].some(field =>
+            !areCmpValuesEqual(fpdFromGlobalObject[field], currentCmpData[field])
+          );
+          if (hasCmpMismatch) {
+            pbjs.refreshUserIds({ submoduleNames: ['intentIqId'] });
+          }
+        }
         break;
+      }
       default:
         break;
     }
@@ -460,9 +471,9 @@ function constructFullUrl(data) {
         PREBID +
         '&uh=' +
         encodeURIComponent(iiqAnalyticsAnalyticsAdapter.initOptions.clientHints) +
-        (cmpData.uspString ? '&us_privacy=' + encodeURIComponent(cmpData.uspString) : '') +
-        (cmpData.gppString ? '&gpp=' + encodeURIComponent(cmpData.gppString) : '') +
-        (cmpData.gdprString ? '&gdpr_consent=' + encodeURIComponent(cmpData.gdprString) + '&gdpr=1' : '&gdpr=0');
+        (isValidValue(cmpData.uspString) ? '&us_privacy=' + encodeURIComponent(cmpData.uspString) : '') +
+        (isValidValue(cmpData.gppString) ? '&gpp=' + encodeURIComponent(cmpData.gppString) : '') +
+        (isValidValue(cmpData.gdprString) ? '&gdpr_consent=' + encodeURIComponent(cmpData.gdprString) + '&gdpr=1' : '&gdpr=0');
 
   url = appendSPData(url, partnerData);
   url = appendVrrefAndFui(url, iiqAnalyticsAnalyticsAdapter.initOptions.domainName);
diff --git a/modules/intentIqIdSystem.js b/modules/intentIqIdSystem.js
index 65b939c684f..57f9c7b1703 100644
--- a/modules/intentIqIdSystem.js
+++ b/modules/intentIqIdSystem.js
@@ -12,7 +12,7 @@ import { detectBrowser } from '../libraries/intentIqUtils/detectBrowserUtils.js'
 import { appendSPData } from '../libraries/intentIqUtils/urlUtils.js';
 import { isCHSupported } from '../libraries/intentIqUtils/chUtils.js'
 import { appendVrrefAndFui } from '../libraries/intentIqUtils/getRefferer.js';
-import { getCmpData } from '../libraries/intentIqUtils/getCmpData.js';
+import { getCmpData, areCmpValuesEqual, isValidValue } from '../libraries/intentIqUtils/getCmpData.js';
 import { readData, storeData, defineStorageType, removeDataByKey, tryParse } from '../libraries/intentIqUtils/storageUtils.js';
 import {
   FIRST_PARTY_KEY,
@@ -112,11 +112,14 @@ function appendPartnersFirstParty(url, configParams) {
 }
 
 function appendCMPData(url, cmpData) {
-  url += cmpData.uspString ? '&us_privacy=' + encodeURIComponent(cmpData.uspString) : '';
-  url += cmpData.gppString ? '&gpp=' + encodeURIComponent(cmpData.gppString) : '';
-  url += cmpData.gdprApplies
-    ? '&gdpr_consent=' + encodeURIComponent(cmpData.gdprString) + '&gdpr=1'
-    : '&gdpr=0';
+  url += isValidValue(cmpData.uspString) ? '&us_privacy=' + encodeURIComponent(cmpData.uspString) : '';
+  url += isValidValue(cmpData.gppString) ? '&gpp=' + encodeURIComponent(cmpData.gppString) : '';
+  if (cmpData.gdprApplies) {
+    url += isValidValue(cmpData.gdprString) ? '&gdpr_consent=' + encodeURIComponent(cmpData.gdprString) : '';
+    url += '&gdpr=1';
+  } else {
+    url += '&gdpr=0';
+  }
   return url
 }
 
@@ -260,9 +263,9 @@ export function handleClientHints(clientHints) {
 }
 
 export function isCMPStringTheSame(fpData, cmpData) {
-  const firstPartyDataCPString = `${fpData.gdprString}${fpData.gppString}${fpData.uspString}`;
-  const cmpDataString = `${cmpData.gdprString}${cmpData.gppString}${cmpData.uspString}`;
-  return firstPartyDataCPString === cmpDataString;
+  return ['gdprString', 'gppString', 'uspString'].every(field =>
+    areCmpValuesEqual(fpData[field], cmpData[field])
+  );
 }
 
 function updateCountersAndStore(runtimeEids, allowedStorage, partnerData) {
diff --git a/test/spec/modules/intentIqAnalyticsAdapter_spec.js b/test/spec/modules/intentIqAnalyticsAdapter_spec.js
index 1853ba511f1..ef0da85de3b 100644
--- a/test/spec/modules/intentIqAnalyticsAdapter_spec.js
+++ b/test/spec/modules/intentIqAnalyticsAdapter_spec.js
@@ -1096,4 +1096,164 @@ describe("IntentIQ tests all", function () {
     expect(decoded.abPercentage).to.equal(95);
     expect(decoded).to.not.have.property('userPercentage');
   });
+
+  describe('BID_REQUESTED CMP mismatch detection', function () {
+    let refreshUserIdsStub;
+    let gppStub, uspStub, gdprStub;
+
+    beforeEach(function () {
+      getGlobal().refreshUserIds = sinon.stub();
+      refreshUserIdsStub = getGlobal().refreshUserIds;
+      gppStub = sinon.stub(gppDataHandler, 'getConsentData').returns(null);
+      uspStub = sinon.stub(uspDataHandler, 'getConsentData').returns(null);
+      gdprStub = sinon.stub(gdprDataHandler, 'getConsentData').returns(null);
+    });
+
+    afterEach(function () {
+      delete getGlobal().refreshUserIds;
+      gppStub.restore();
+      uspStub.restore();
+      gdprStub.restore();
+    });
+
+    it('should call refreshUserIds with intentIqId when gdprString changes', function () {
+      window[identityName].firstPartyData.gdprString = 'oldConsent';
+      gdprStub.returns({ consentString: 'newConsent', gdprApplies: true });
+
+      events.emit(EVENTS.BID_REQUESTED);
+
+      expect(refreshUserIdsStub.calledOnce).to.be.true;
+      expect(refreshUserIdsStub.calledWith({ submoduleNames: ['intentIqId'] })).to.be.true;
+    });
+
+    it('should call refreshUserIds when uspString changes from valid to another valid value', function () {
+      window[identityName].firstPartyData.uspString = '1YNN';
+      uspStub.returns('1NNN');
+
+      events.emit(EVENTS.BID_REQUESTED);
+
+      expect(refreshUserIdsStub.calledOnce).to.be.true;
+    });
+
+    it('should not call refreshUserIds when CMP data matches stored firstPartyData', function () {
+      window[identityName].firstPartyData.gdprString = 'sameConsent';
+      window[identityName].firstPartyData.gppString = null;
+      window[identityName].firstPartyData.uspString = null;
+      gdprStub.returns({ consentString: 'sameConsent', gdprApplies: true });
+
+      events.emit(EVENTS.BID_REQUESTED);
+
+      expect(refreshUserIdsStub.called).to.be.false;
+    });
+
+    it('should not call refreshUserIds when null and empty string are compared (both invalid)', function () {
+      window[identityName].firstPartyData.gdprString = null;
+      window[identityName].firstPartyData.gppString = null;
+      window[identityName].firstPartyData.uspString = null;
+
+      events.emit(EVENTS.BID_REQUESTED);
+
+      expect(refreshUserIdsStub.called).to.be.false;
+    });
+
+    it('should not call refreshUserIds when stored value is "undefined" string and current is null (both invalid)', function () {
+      window[identityName].firstPartyData.gdprString = '';
+      window[identityName].firstPartyData.gppString = 'undefined';
+      window[identityName].firstPartyData.uspString = 'undefined';
+
+      events.emit(EVENTS.BID_REQUESTED);
+
+      expect(refreshUserIdsStub.called).to.be.false;
+    });
+
+    it('should call refreshUserIds when valid gdprString is replaced by null (invalid)', function () {
+      window[identityName].firstPartyData.gdprString = 'validConsent';
+      window[identityName].firstPartyData.gppString = null;
+      window[identityName].firstPartyData.uspString = null;
+
+      events.emit(EVENTS.BID_REQUESTED);
+
+      expect(refreshUserIdsStub.calledOnce).to.be.true;
+    });
+
+    it('should not call refreshUserIds when firstPartyData is absent in global object', function () {
+      delete window[identityName].firstPartyData;
+
+      events.emit(EVENTS.BID_REQUESTED);
+
+      expect(refreshUserIdsStub.called).to.be.false;
+    });
+  });
+
+  describe('constructFullUrl CMP isValidValue filtering', function () {
+    let gppStub, uspStub, gdprStub;
+
+    afterEach(function () {
+      if (gppStub) gppStub.restore();
+      if (uspStub) uspStub.restore();
+      if (gdprStub) gdprStub.restore();
+    });
+
+    it('should not include us_privacy when uspString is null', function () {
+      uspStub = sinon.stub(uspDataHandler, 'getConsentData').returns(null);
+      gppStub = sinon.stub(gppDataHandler, 'getConsentData').returns(null);
+      gdprStub = sinon.stub(gdprDataHandler, 'getConsentData').returns(null);
+
+      events.emit(EVENTS.BID_WON, getWonRequest());
+
+      expect(server.requests[0].url).to.not.include('us_privacy');
+    });
+
+    it('should not include us_privacy when uspString is the string "undefined"', function () {
+      uspStub = sinon.stub(uspDataHandler, 'getConsentData').returns('undefined');
+      gppStub = sinon.stub(gppDataHandler, 'getConsentData').returns(null);
+      gdprStub = sinon.stub(gdprDataHandler, 'getConsentData').returns(null);
+
+      events.emit(EVENTS.BID_WON, getWonRequest());
+
+      expect(server.requests[0].url).to.not.include('us_privacy');
+    });
+
+    it('should not include gpp when gppString is null', function () {
+      uspStub = sinon.stub(uspDataHandler, 'getConsentData').returns(null);
+      gppStub = sinon.stub(gppDataHandler, 'getConsentData').returns(null);
+      gdprStub = sinon.stub(gdprDataHandler, 'getConsentData').returns(null);
+
+      events.emit(EVENTS.BID_WON, getWonRequest());
+
+      expect(server.requests[0].url).to.not.include('&gpp=');
+    });
+
+    it('should not include gdpr_consent when gdprString is null', function () {
+      uspStub = sinon.stub(uspDataHandler, 'getConsentData').returns(null);
+      gppStub = sinon.stub(gppDataHandler, 'getConsentData').returns(null);
+      gdprStub = sinon.stub(gdprDataHandler, 'getConsentData').returns(null);
+
+      events.emit(EVENTS.BID_WON, getWonRequest());
+
+      expect(server.requests[0].url).to.not.include('gdpr_consent');
+    });
+
+    it('should not include gdpr_consent when gdprString is the string "undefined"', function () {
+      uspStub = sinon.stub(uspDataHandler, 'getConsentData').returns(null);
+      gppStub = sinon.stub(gppDataHandler, 'getConsentData').returns(null);
+      gdprStub = sinon.stub(gdprDataHandler, 'getConsentData').returns({ consentString: 'undefined', gdprApplies: false });
+
+      events.emit(EVENTS.BID_WON, getWonRequest());
+
+      expect(server.requests[0].url).to.not.include('gdpr_consent');
+    });
+
+    it('should include gdpr_consent and gdpr=1 when gdprString is valid', function () {
+      const consentString = 'validConsent';
+      uspStub = sinon.stub(uspDataHandler, 'getConsentData').returns(null);
+      gppStub = sinon.stub(gppDataHandler, 'getConsentData').returns(null);
+      gdprStub = sinon.stub(gdprDataHandler, 'getConsentData').returns({ consentString, gdprApplies: true });
+
+      events.emit(EVENTS.BID_WON, getWonRequest());
+
+      expect(server.requests[0].url).to.include(`gdpr_consent=${encodeURIComponent(consentString)}`);
+      expect(server.requests[0].url).to.include('gdpr=1');
+    });
+  });
 });
diff --git a/test/spec/modules/intentIqIdSystem_spec.js b/test/spec/modules/intentIqIdSystem_spec.js
index e0e56338a3c..8325ec780aa 100644
--- a/test/spec/modules/intentIqIdSystem_spec.js
+++ b/test/spec/modules/intentIqIdSystem_spec.js
@@ -1345,6 +1345,103 @@ describe('IntentIQ tests', function () {
     expect(isCMPStringTheSame(fpData, cmpData)).to.be.false;
   });
 
+  it('should return true when null and empty string are compared (both invalid)', function () {
+    const fpData = { gdprString: null, gppString: null, uspString: null };
+    const cmpData = { gdprString: '', gppString: '', uspString: '' };
+
+    expect(isCMPStringTheSame(fpData, cmpData)).to.be.true;
+  });
+
+  it('should return true when null and undefined are compared (both invalid)', function () {
+    const fpData = { gdprString: null, gppString: null, uspString: null };
+    const cmpData = { gdprString: undefined, gppString: undefined, uspString: undefined };
+
+    expect(isCMPStringTheSame(fpData, cmpData)).to.be.true;
+  });
+
+  it('should return true when "undefined" string and null are compared (both invalid)', function () {
+    const fpData = { gdprString: 'undefined', gppString: 'undefined', uspString: 'undefined' };
+    const cmpData = { gdprString: null, gppString: null, uspString: null };
+
+    expect(isCMPStringTheSame(fpData, cmpData)).to.be.true;
+  });
+
+  it('should return false when a valid value is compared against null', function () {
+    const fpData = { gdprString: 'consent123', gppString: null, uspString: null };
+    const cmpData = { gdprString: null, gppString: null, uspString: null };
+
+    expect(isCMPStringTheSame(fpData, cmpData)).to.be.false;
+  });
+
+  it('should return false when null is compared against a valid value', function () {
+    const fpData = { gdprString: null, gppString: null, uspString: null };
+    const cmpData = { gdprString: 'consent123', gppString: null, uspString: null };
+
+    expect(isCMPStringTheSame(fpData, cmpData)).to.be.false;
+  });
+
+  describe('appendCMPData via createPixelUrl', function () {
+    const baseParams = { partner: 'testPartner', domainName: 'example.com' };
+
+    it('should not include us_privacy in URL when uspString is null', function () {
+      const cmpData = { uspString: null, gppString: null, gdprApplies: false, gdprString: null };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.not.include('us_privacy');
+    });
+
+    it('should not include us_privacy in URL when uspString is the string "undefined"', function () {
+      const cmpData = { uspString: 'undefined', gppString: null, gdprApplies: false, gdprString: null };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.not.include('us_privacy');
+    });
+
+    it('should include us_privacy in URL when uspString is a valid string', function () {
+      const cmpData = { uspString: '1NYN', gppString: null, gdprApplies: false, gdprString: null };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.include(`&us_privacy=${encodeURIComponent('1NYN')}`);
+    });
+
+    it('should not include gpp in URL when gppString is null', function () {
+      const cmpData = { uspString: null, gppString: null, gdprApplies: false, gdprString: null };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.not.include('&gpp=');
+    });
+
+    it('should not include gpp in URL when gppString is the string "undefined"', function () {
+      const cmpData = { uspString: null, gppString: 'undefined', gdprApplies: false, gdprString: null };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.not.include('&gpp=');
+    });
+
+    it('should include gdpr=1 without gdpr_consent when gdprApplies is true and gdprString is null', function () {
+      const cmpData = { uspString: null, gppString: null, gdprApplies: true, gdprString: null };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.include('&gdpr=1');
+      expect(url).to.not.include('gdpr_consent');
+    });
+
+    it('should include gdpr=1 without gdpr_consent when gdprApplies is true and gdprString is "undefined"', function () {
+      const cmpData = { uspString: null, gppString: null, gdprApplies: true, gdprString: 'undefined' };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.include('&gdpr=1');
+      expect(url).to.not.include('gdpr_consent');
+    });
+
+    it('should include gdpr=1 and gdpr_consent when gdprApplies is true and gdprString is valid', function () {
+      const cmpData = { uspString: null, gppString: null, gdprApplies: true, gdprString: 'validConsent' };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.include('&gdpr=1');
+      expect(url).to.include(`&gdpr_consent=${encodeURIComponent('validConsent')}`);
+    });
+
+    it('should include gdpr=0 and no gdpr_consent when gdprApplies is false', function () {
+      const cmpData = { uspString: null, gppString: null, gdprApplies: false, gdprString: null };
+      const url = createPixelUrl({}, undefined, baseParams, {}, cmpData);
+      expect(url).to.include('&gdpr=0');
+      expect(url).to.not.include('gdpr_consent');
+    });
+  });
+
   it('should run callback from params', async () => {
     let wasCallbackCalled = false
     const callbackConfigParams = {