diff --git a/client/api/index.js b/client/api/index.js
index 2d6ebe7c20..3652653eec 100644
--- a/client/api/index.js
+++ b/client/api/index.js
@@ -536,6 +536,19 @@ export default class WCStripeAPI {
 		} );
 	}
 
+	/**
+	 * Update cart customer data.
+	 *
+	 * @param {Object} customerData Customer data.
+	 * @return {Promise} Promise for the request to the server.
+	 */
+	expressCheckoutUpdateCartCustomer( customerData ) {
+		return this.postToBlocksAPI(
+			'/wc/store/v1/cart/update-customer',
+			customerData
+		);
+	}
+
 	/**
 	 * Add product to cart from product page.
 	 *
diff --git a/client/entrypoints/express-checkout/index.js b/client/entrypoints/express-checkout/index.js
index 7666fc0b07..d334f10f48 100644
--- a/client/entrypoints/express-checkout/index.js
+++ b/client/entrypoints/express-checkout/index.js
@@ -8,10 +8,12 @@ import { __ } from '@wordpress/i18n';
 import {
 	displayExpressCheckoutNotice,
 	displayLoginConfirmation,
+	getBillingAddressData,
 	getExpressCheckoutButtonAppearance,
 	getExpressCheckoutButtonStyleSettings,
 	getExpressCheckoutData,
 	getPaymentMethodTypesForExpressMethod,
+	getTotalPriceFromCart,
 	isManualPaymentMethodCreation,
 	normalizeLineItems,
 } from 'wcstripe/express-checkout/utils';
@@ -35,11 +37,11 @@ import {
 	EXPRESS_PAYMENT_METHOD_SETTING_APPLE_PAY,
 	EXPRESS_PAYMENT_METHOD_SETTING_GOOGLE_PAY,
 	EXPRESS_PAYMENT_METHOD_SETTING_LINK,
+	PAYMENT_METHOD_AMAZON_PAY,
 } from 'wcstripe/stripe-utils/constants';
 import {
 	transformCartDataForDisplayItems,
 	transformLabeledDisplayItems,
-	transformPrice,
 } from 'wcstripe/express-checkout/transformers/wc-to-stripe';
 
 jQuery( function ( $ ) {
@@ -456,6 +458,43 @@ jQuery( function ( $ ) {
 					}
 				}
 
+				// When taxes are based on the billing address and Amazon Pay is used, we need to update the cart customer data and recompute taxes
+				// before we can finalise the payment.
+				if (
+					getExpressCheckoutData( 'taxes_based_on_billing' ) &&
+					event?.expressPaymentType === PAYMENT_METHOD_AMAZON_PAY
+				) {
+					const initialBillingAddress =
+						getBillingAddressData( event );
+
+					// Pass the billing address through our standard express checkout address normalization process.
+					const normalizedBillingData =
+						await api.expressCheckoutNormalizeAddress(
+							initialBillingAddress,
+							{}
+						);
+
+					// Update the cart customer data with the normalized billing address, with the initial address as a fallback.
+					const customerData = {
+						billing_address:
+							normalizedBillingData.billing_address ||
+							initialBillingAddress,
+					};
+					const customerUpdateResult =
+						await api.expressCheckoutUpdateCartCustomer(
+							customerData
+						);
+
+					if ( customerUpdateResult?.totals ) {
+						const updatedPrice =
+							getTotalPriceFromCart( customerUpdateResult );
+
+						await elements.update( {
+							amount: updatedPrice,
+						} );
+					}
+				}
+
 				const order = options.order ? options.order : 0;
 				const orderDetails = options.orderDetails ?? {};
 				return await onConfirmHandler( {
@@ -560,11 +599,7 @@ jQuery( function ( $ ) {
 			} else {
 				// Cart and Checkout page specific initialization.
 				api.expressCheckoutGetCartDetails().then( ( cart ) => {
-					const total = transformPrice(
-						parseInt( cart.totals.total_price, 10 ) -
-							parseInt( cart.totals.total_refund || 0, 10 ),
-						cart.totals
-					);
+					const total = getTotalPriceFromCart( cart );
 
 					if (
 						total === 0 &&
diff --git a/client/express-checkout/utils/index.js b/client/express-checkout/utils/index.js
index 79baddbd72..e6c6bea18a 100644
--- a/client/express-checkout/utils/index.js
+++ b/client/express-checkout/utils/index.js
@@ -2,6 +2,7 @@
 import jQuery from 'jquery';
 import { isAmazonPayEnabled, isLinkEnabled } from 'wcstripe/stripe-utils';
 import { EXPRESS_CHECKOUT_NOTICE_DELAY } from 'wcstripe/data/constants';
+import { transformPrice } from 'wcstripe/express-checkout/transformers/wc-to-stripe';
 import {
 	EXPRESS_PAYMENT_METHOD_SETTING_AMAZON_PAY,
 	EXPRESS_PAYMENT_METHOD_SETTING_APPLE_PAY,
@@ -404,3 +405,17 @@ export const isManualPaymentMethodCreation = (
 		].includes( expressPaymentType ) || hasFreeTrial
 	);
 };
+
+/**
+ * Get the total price from a cart response.
+ *
+ * @param {Object} cart The cart response from the server.
+ * @return {number} The total price.
+ */
+export const getTotalPriceFromCart = ( cart ) => {
+	return transformPrice(
+		parseInt( cart.totals.total_price, 10 ) -
+			parseInt( cart.totals.total_refund || 0, 10 ),
+		cart.totals
+	);
+};
diff --git a/client/express-checkout/utils/normalize.js b/client/express-checkout/utils/normalize.js
index 9232fc179c..ff009cdb07 100644
--- a/client/express-checkout/utils/normalize.js
+++ b/client/express-checkout/utils/normalize.js
@@ -346,7 +346,7 @@ export const normalizeShippingAddress = ( shippingAddress ) => {
  *
  * @return {Object} The billing address data.
  */
-const getBillingAddressData = ( event ) => {
+export const getBillingAddressData = ( event ) => {
 	const name = event?.billingDetails?.name;
 	const email = event?.billingDetails?.email ?? '';
 	const billing = event?.billingDetails?.address ?? {};