diff --git a/ghost/stripe/lib/StripeAPI.js b/ghost/stripe/lib/StripeAPI.js
index b5ae3be4ed..3a0b31f64f 100644
--- a/ghost/stripe/lib/StripeAPI.js
+++ b/ghost/stripe/lib/StripeAPI.js
@@ -364,7 +364,9 @@ module.exports = class StripeAPI {
      */
     async createCheckoutSession(priceId, customer, options) {
         const metadata = options.metadata || undefined;
+        const customerId = customer ? customer.id : undefined;
         const customerEmail = customer ? customer.email : options.customerEmail;
+ 
         await this._rateLimitBucket.throttle();
         let discounts;
         if (options.coupon) {
@@ -386,11 +388,11 @@ module.exports = class StripeAPI {
             delete subscriptionData.trial_from_plan;
             subscriptionData.trial_period_days = options.trialDays;
         }
-        const session = await this._stripe.checkout.sessions.create({
+
+        let stripeSessionOptions = {
             payment_method_types: ['card'],
             success_url: options.successUrl || this._config.checkoutSessionSuccessUrl,
             cancel_url: options.cancelUrl || this._config.checkoutSessionCancelUrl,
-            customer_email: customerEmail,
             // @ts-ignore - we need to update to latest stripe library to correctly use newer features
             allow_promotion_codes: discounts ? undefined : this._config.enablePromoCodes,
             metadata,
@@ -405,7 +407,17 @@ module.exports = class StripeAPI {
             // however, this would lose the "trial from plan" feature which has also
             // been deprecated by Stripe
             subscription_data: subscriptionData
-        });
+        };
+
+        /* We are only allowed to specify one of these; email will be pulled from
+           customer object on Stripe side if that object already exists. */
+        if (customerId) {
+            stripeSessionOptions.customer = customerId;
+        } else {
+            stripeSessionOptions.customer_email = customerEmail;
+        }
+
+        const session = await this._stripe.checkout.sessions.create(stripeSessionOptions);
 
         return session;
     }
diff --git a/ghost/stripe/test/unit/lib/StripeAPI.test.js b/ghost/stripe/test/unit/lib/StripeAPI.test.js
index 76bd89de91..f834b67c36 100644
--- a/ghost/stripe/test/unit/lib/StripeAPI.test.js
+++ b/ghost/stripe/test/unit/lib/StripeAPI.test.js
@@ -80,4 +80,59 @@ describe('StripeAPI', function () {
         should.equal(mockStripe.checkout.sessions.create.firstCall.firstArg.subscription_data.trial_from_plan, true);
         should.not.exist(mockStripe.checkout.sessions.create.firstCall.firstArg.subscription_data.trial_period_days);
     });
+
+    it('createCheckoutSession passes customer ID successfully to Stripe', async function (){
+        const mockCustomer = {
+            id: 'cust_mock_123456',
+            customer_email: 'foo@example.com',
+            name: 'Example Customer'
+        };
+
+        await api.createCheckoutSession('priceId', mockCustomer, {
+            trialDays: null
+        });
+
+        should.exist(mockStripe.checkout.sessions.create.firstCall.firstArg.customer);
+        should.equal(mockStripe.checkout.sessions.create.firstCall.firstArg.customer, 'cust_mock_123456');
+    });
+
+    it('createCheckoutSession passes email if no customer object provided', async function (){
+        await api.createCheckoutSession('priceId', undefined, {
+            customerEmail: 'foo@example.com',
+            trialDays: null
+        });
+
+        should.exist(mockStripe.checkout.sessions.create.firstCall.firstArg.customer_email);
+        should.equal(mockStripe.checkout.sessions.create.firstCall.firstArg.customer_email, 'foo@example.com');
+    });
+
+    it('createCheckoutSession passes email if customer object provided w/o ID', async function (){
+        const mockCustomer = {
+            email: 'foo@example.com',
+            name: 'Example Customer'
+        };
+
+        await api.createCheckoutSession('priceId', mockCustomer, {
+            trialDays: null
+        });
+
+        should.exist(mockStripe.checkout.sessions.create.firstCall.firstArg.customer_email);
+        should.equal(mockStripe.checkout.sessions.create.firstCall.firstArg.customer_email, 'foo@example.com');
+    });
+
+    it('createCheckoutSession passes only one of customer ID and email', async function (){
+        const mockCustomer = {
+            id: 'cust_mock_123456',
+            email: 'foo@example.com',
+            name: 'Example Customer'
+        };
+
+        await api.createCheckoutSession('priceId', mockCustomer, {
+            trialDays: null
+        });
+
+        should.not.exist(mockStripe.checkout.sessions.create.firstCall.firstArg.customer_email);
+        should.exist(mockStripe.checkout.sessions.create.firstCall.firstArg.customer);
+        should.equal(mockStripe.checkout.sessions.create.firstCall.firstArg.customer, 'cust_mock_123456');
+    });
 });