diff --git a/src/constants/store-actions.js b/src/constants/store-actions.js
index 3afd4df24..26bcc25e1 100644
--- a/src/constants/store-actions.js
+++ b/src/constants/store-actions.js
@@ -123,6 +123,8 @@ const storeActions = {
 
     SAVE_LOGGING_OPTION: "saveLoggingOption",
     UPDATE_HAS_TRIGGERED_ERROR: "updateHasTriggeredError",
+    GET_VALID_IDEMPOTENCY_KEY: "getValidIdempotencyKey",
+    CORRECT_IDEMPOTENCY_KEY_EXPIRY: "correctIdempotencyKeyExpiry",
 };
 
 export { storeActions };
diff --git a/src/constants/store-mutations.js b/src/constants/store-mutations.js
index 9b4b3719c..5c6c2e22d 100644
--- a/src/constants/store-mutations.js
+++ b/src/constants/store-mutations.js
@@ -98,6 +98,7 @@ const storeMutations = {
     UPDATE_LAST_PAGE_VISITED: "updateLastPageVisited",
     UPDATE_LOGGING_OPTION: "updateLoggingOption",
     UPDATE_HAS_TRIGGERED_ERROR: "updateHasTriggeredError",
+    UPDATE_IDEMPOTENCY_KEY: "updateIdempotencyKey",
 
     // EXPERIMENT MUTATIONS
     UPDATE_EXPERIMENTS: "updateExperiments",
diff --git a/src/layouts/payment-adyen/payment-adyen.vue b/src/layouts/payment-adyen/payment-adyen.vue
index adb0a1210..4a4936a7f 100644
--- a/src/layouts/payment-adyen/payment-adyen.vue
+++ b/src/layouts/payment-adyen/payment-adyen.vue
@@ -163,7 +163,7 @@ export default {
             console.log(`Price = ${this.amountDue}`);
             console.log(`Adyen Price = ${this.adyenPriceTotal}`);
 
-            const requestBody = this.getAdyenInitRequestInfo();
+            const requestBody = await this.getAdyenInitRequestInfo();
 
             console.log(`Calling with:`);
             console.log(requestBody);
@@ -257,6 +257,7 @@ export default {
             this.dropinComponent = dropin;
 
             dropin.mount("#adyen-container");
+            await this.dispatchStoreAction(storeActions.CORRECT_IDEMPOTENCY_KEY_EXPIRY, expiryTime);
         },
 
         async handleCompletedPayment(result) {
@@ -438,19 +439,13 @@ export default {
         },
 
         // Now a Method so it is always freshly called and not cached.
-        getIdempotencyKey() {
-            const currentDateTime = new Date();
-            const currentHour = currentDateTime.getUTCHours();
-            const currentDate = currentDateTime.getUTCDate();
-            const id = this?.$store?.getters?.order?.referralCorrelationId;
-            const system = this.sourceSystem;
-            const total = this.adyenPriceTotal;
-
-            return `${id}-${system}-${currentDate}-${currentHour}-${total}`;
+        async getIdempotencyKey() {
+            return await this.dispatchStoreAction(storeActions.GET_VALID_IDEMPOTENCY_KEY);
         },
 
         // Now a Method so it is always freshly called and not cached.
-        getAdyenInitRequestInfo() {
+        async getAdyenInitRequestInfo() {
+            const key = await this.getIdempotencyKey();
             return {
                 sourceSystem: this.sourceSystem,
                 referralSequenceNumber: this.$store.getters.order.referralSequenceNumber,
@@ -464,10 +459,9 @@ export default {
                 stateOrProvince: this.locationInfo.state,
                 returnUrl: applicationConfig.PIA_ADYEN_RETURN_URL,
                 email: this.$store.getters.order.customer.emailAddress,
-                IP: "127.0.0.1", // TODO
                 firstName: this.$store.getters.order.customer.firstName,
                 lastName: this.$store.getters.order.customer.lastName,
-                idempotencyKey: this.getIdempotencyKey(),
+                idempotencyKey: key,
             };
         },
     },
diff --git a/src/store/index.js b/src/store/index.js
index 10218892c..e740bf0d3 100644
--- a/src/store/index.js
+++ b/src/store/index.js
@@ -59,7 +59,7 @@ import {
 } from "@/helpers/recal-helper";
 import { externalParameterStatus } from "@/constants/external-parameters";
 import { experimentSettings } from "@/constants/experiments";
-import { addPricesToLineItems } from "@/helpers/pricing-helper";
+import { addPricesToLineItems, getAmountDue } from "@/helpers/pricing-helper";
 
 // Export State
 const getDefaultState = () => {
@@ -207,6 +207,12 @@ const getDefaultState = () => {
             loggingOption: false,
             hasAlreadyTriggeredError: false,
         },
+        idempotencyKeyFields: {
+            referralCorrelationId: null,
+            totalInCents: 0,
+            expiryTime: null,
+            idempotencyKey: null,
+        },
     };
 };
 
@@ -862,6 +868,15 @@ export const mutations = {
     updateHasTriggeredError(state, hasTriggeredError) {
         state.applicationUser.hasAlreadyTriggeredError = hasTriggeredError;
     },
+    updateIdempotencyKey(
+        state,
+        { idempotencyKey, referralCorrelationId, totalInCents, expiryTime }
+    ) {
+        state.idempotencyKeyFields.idempotencyKey = idempotencyKey;
+        state.idempotencyKeyFields.referralCorrelationId = referralCorrelationId;
+        state.idempotencyKeyFields.totalInCents = totalInCents;
+        state.idempotencyKeyFields.expiryTime = expiryTime;
+    },
 };
 
 // Export Getters
@@ -1105,6 +1120,35 @@ export const getters = {
             state.order.customer.emailAddress
         );
     },
+
+    isIdempotencyKeyValid: (state) => {
+        if (!state.idempotencyKeyFields?.idempotencyKey) {
+            return false;
+        }
+
+        const referralCorrelationId = state.order?.referralCorrelationId;
+        if (
+            !referralCorrelationId ||
+            referralCorrelationId !== state.idempotencyKeyFields?.referralCorrelationId
+        ) {
+            return false;
+        }
+
+        const total = getAmountDue(state.order?.lineItems);
+        const totalInCents = Math.round(total * 100);
+        if (totalInCents !== state.idempotencyKeyFields?.totalInCents) {
+            return false;
+        }
+
+        const currentTime = new Date();
+        const expiryTime = new Date(state.idempotencyKeyFields.expiryTime);
+        if (!expiryTime || expiryTime.getTime() < currentTime.getTime()) {
+            return false;
+        }
+
+        // If all checks pass, then the key is valid.
+        return true;
+    },
 };
 
 // Export Actions
@@ -3665,6 +3709,63 @@ export const actions = {
     updateHasTriggeredError(context, hasAlreadyTriggeredError) {
         context.commit(storeMutations.UPDATE_HAS_TRIGGERED_ERROR, hasAlreadyTriggeredError);
     },
+
+    getValidIdempotencyKey(context) {
+        if (context.getters.isIdempotencyKeyValid) {
+            return context.state.idempotencyKeyFields.idempotencyKey;
+        }
+
+        // If invalid, need to regenerate.
+        const referralCorrelationId = context.state.order?.referralCorrelationId;
+        if (!referralCorrelationId) {
+            // Can't generate!
+            return null;
+        }
+
+        const total = getAmountDue(context.state.order?.lineItems);
+        const totalInCents = Math.round(total * 100);
+        if (Number.isNaN(totalInCents)) {
+            // Can't generate!
+            return null;
+        }
+
+        const currentTime = new Date();
+        const nextHour = currentTime.getUTCHours() + 1;
+        currentTime.setUTCHours(nextHour);
+
+        const newId = crypto.randomUUID();
+
+        const newKeyInfo = {
+            idempotencyKey: newId,
+            referralCorrelationId: referralCorrelationId,
+            totalInCents: totalInCents,
+            expiryTime: currentTime,
+        };
+
+        context.commit(storeMutations.UPDATE_IDEMPOTENCY_KEY, newKeyInfo);
+
+        return newId;
+    },
+
+    correctIdempotencyKeyExpiry(context, expiryTime) {
+        if (!context.getters.isIdempotencyKeyValid) {
+            return;
+        }
+
+        const currentExpiryTime = new Date(context.state.idempotencyKeyFields.expiryTime);
+        const expiryTimeAsDate = new Date(expiryTime);
+
+        if (expiryTimeAsDate.getTime() < currentExpiryTime.getTime()) {
+            const existingKey = context.state.idempotencyKeyFields;
+            const newKey = {
+                referralCorrelationId: existingKey.referralCorrelationId,
+                totalInCents: existingKey.totalInCents,
+                idempotencyKey: existingKey.idempotencyKey,
+                expiryTime: expiryTimeAsDate,
+            };
+            context.commit(storeMutations.UPDATE_IDEMPOTENCY_KEY, newKey);
+        }
+    },
 };
 
 export default createStore({