diff --git a/android/src/main/java/com/nextar/sumup/RNSumUpModule.java b/android/src/main/java/com/nextar/sumup/RNSumUpModule.java
index 63a73c9..69dc7e6 100644
--- a/android/src/main/java/com/nextar/sumup/RNSumUpModule.java
+++ b/android/src/main/java/com/nextar/sumup/RNSumUpModule.java
@@ -134,15 +134,22 @@ private SumUpPayment.Currency getCurrency(String currency) {
 
   @ReactMethod
   public void checkout(ReadableMap request, Promise promise) {
-    // TODO: replace foreignTransactionId for transaction UUID sent by user.
     mSumUpPromise = promise;
     try {
+      String foreignTransactionId = UUID.randomUUID().toString();
+      if (request.getString("foreignTransactionId") != null) {
+         foreignTransactionId = request.getString("foreignTransactionId");
+      }
       SumUpPayment.Currency currencyCode = this.getCurrency(request.getString("currencyCode"));
       SumUpPayment payment = SumUpPayment.builder()
               .total(new BigDecimal(request.getString("totalAmount")).setScale(2, RoundingMode.HALF_EVEN))
               .currency(currencyCode)
               .title(request.getString("title"))
-              .foreignTransactionId(UUID.randomUUID().toString())
+              // Wait for ios imp
+              // .addAdditionalInfo("AccountId", "taxi0334")
+              // .receiptEmail("customer@mail.com")
+              // .receiptSMS("+3531234567890")
+              .foreignTransactionId(foreignTransactionId)
               .skipSuccessScreen()
               .build();
       SumUpAPI.checkout(getCurrentActivity(), payment, REQUEST_CODE_PAYMENT);
diff --git a/ios/RNSumUp.m b/ios/RNSumUp.m
index 22d1030..6834d98 100644
--- a/ios/RNSumUp.m
+++ b/ios/RNSumUp.m
@@ -124,6 +124,7 @@ - (NSDictionary *)constantsToExport
     NSDecimalNumber *total = [NSDecimalNumber decimalNumberWithString:[RCTConvert NSString:request[@"totalAmount"]]];
     NSString *title = [RCTConvert NSString:request[@"title"]];
     NSString *currencyCode = [RCTConvert NSString:request[@"currencyCode"]];
+    NSString *foreignTransactionID = [RCTConvert NSString:[request objectForKeyNotNull:@"foreignTransactionId"]];
     NSUInteger paymentOption = [RCTConvert SMPPaymentOptions:request[@"paymentOption"]];
     NSUInteger skipScreen = [RCTConvert SMPSkipScreenOptions:@"1"];
 
@@ -132,6 +133,10 @@ - (NSDictionary *)constantsToExport
                                                                   currencyCode:currencyCode
                                                                 paymentOptions:paymentOption];
     checkoutRequest.skipScreenOptions = skipScreen;
+    if (foreignTransactionID != [NSNull null]) {
+        [checkoutRequest setForeignTransactionID:foreignTransactionID];
+    }
+
     dispatch_sync(dispatch_get_main_queue(), ^{
         UIViewController *rootViewController = UIApplication.sharedApplication.delegate.window.rootViewController;
         while (rootViewController.presentedViewController != nil) {