diff --git a/src/store/index.js b/src/store/index.js
index e0d32e74..623d7963 100644
--- a/src/store/index.js
+++ b/src/store/index.js
@@ -118,7 +118,8 @@ export const getDefaultState = () => ({
             cvrgEndorsementCode: null,
             status: null,
             policyData: null,
-            policyLookupErrorCode: 0
+            policyLookupErrorCode: 0,
+            memberNumber: null
         },
         customer: {
             address: {
@@ -585,9 +586,9 @@ export const useMainStore = defineStore({
                     referralCorrelationId: order.referralCorrelationId,
                     referralNumber: order.referralNumber
                 };
-                // Clients (i.e. USAA) may sometimes use member number, which is just policy number by a different name
+                // Clients (i.e. USAA) may sometimes use member number in addition to a policy number
                 if (this.issConfig.useMemberNumber) {
-                    payload.memberNumber = policy.policyNumber;
+                    payload.memberNumber = policy.memberNumber ?? policy.policyNumber;
                 }
                 const response = await globalMethods.callHttpClient({
                     method: endpoints.CoveragePolicyInfo.method,
@@ -617,6 +618,15 @@ export const useMainStore = defineStore({
 
                     // populate additional fields
                     order.policy.policyData = responsePolicy.policyData;
+                    if (this.issConfig.useMemberNumber) {
+                        if (!order.policy.memberNumber) {
+                            // We capture the member number (entered as policy number) once, so we don't overwrite it with returned policy number on subsequent lookups
+                            order.policy.memberNumber = order.policy.policyNumber;
+                        }
+                        if (responsePolicy.policyNumber != null) {
+                            order.policy.policyNumber = responsePolicy.policyNumber;
+                        }
+                    }
 
                     // populate vehicles
                     order.policy.vehicles = responsePolicy.vehicles ?? [];
@@ -714,9 +724,9 @@ export const useMainStore = defineStore({
                     fleetNumber: this.order.vehicle.fleetNumber,
                     fleetUnitNumber: this.order.vehicle.fleetUnitNumber
                 };
-                // Clients (i.e. USAA) may sometimes use member number, which is just policy number by a different name
+                // Clients (i.e. USAA) may sometimes use member number in addition to a policy number
                 if (this.issConfig.useMemberNumber) {
-                    payload.memberNumber = this.order.policy.policyNumber;
+                    payload.memberNumber = this.order.policy.memberNumber ?? this.order.policy.policyNumber;
                 }
                 await updateClientSpecificFieldsForClaimRegistration(payload, this.order);
                 const response = await globalMethods.callHttpClient({
@@ -775,9 +785,9 @@ export const useMainStore = defineStore({
                 policyData: this.order.policy.policyData,
                 isItac: this.isITAC
             };
-            // Clients (i.e. USAA) may sometimes use member number, which is just policy number by a different name
+            // Clients (i.e. USAA) may sometimes use member number in addition to a policy number
             if (this.issConfig.useMemberNumber) {
-                payload.memberNumber = this.order.policy.policyNumber;
+                payload.memberNumber = this.order.policy.memberNumber ?? this.order.policy.policyNumber;
             }
 
             try {
@@ -2207,6 +2217,7 @@ export const useMainStore = defineStore({
             this.order.policy.policyLookupErrorCode = 0;
             this.order.policy.deductible.repair = null;
             this.order.policy.deductible.replace = null;
+            this.order.policy.memberNumber = null;
         },
 
         resetPayment() {
diff --git a/src/store/store.spec.js b/src/store/store.spec.js
index 78345ff4..a443e9b9 100644
--- a/src/store/store.spec.js
+++ b/src/store/store.spec.js
@@ -1496,6 +1496,41 @@ describe('Store', () => {
                     })
                 }));
             });
+            it('useMemberNumber is true => member number set and policy number changed after response', async () => {
+                // Arrange
+                const originalPolicyNumber = getRandomString(6, 6);
+                store.order.policy.policyNumber = originalPolicyNumber;
+                const returnedPolicyNumber = getRandomString(6, 6);
+                const responseWithPolicy = {
+                    data: {
+                        policies: [{
+                            policyNumber: returnedPolicyNumber
+                        }]
+                    }
+                };
+                store.issConfig.isCoverageEnabled = true;
+                store.applicationUser.coverageLookupAttempts = 0;
+                store.issConfig.useMemberNumber = true;
+                globalMethods.callHttpClient = jest.fn().mockReturnValue(Promise.resolve(responseWithPolicy));
+
+                // Act
+                await store.getCoveragePolicyInfo();
+
+                // Asserts
+                expect(store.order.policy.memberNumber).toBe(originalPolicyNumber);
+                expect(store.order.policy.policyNumber).toBe(returnedPolicyNumber);
+
+                // Act again
+                await store.getCoveragePolicyInfo();
+
+                // Assert again
+                expect(globalMethods.callHttpClient).toHaveBeenNthCalledWith(2, expect.objectContaining({
+                    payload: expect.objectContaining({
+                        policyNumber: returnedPolicyNumber,
+                        memberNumber: originalPolicyNumber
+                    })
+                }));
+            });
             it('null response by api => insuranceCoverage.coverageType is NONE', async () => {
                 // Arrange
                 store.issConfig.isCoverageEnabled = true;