diff --git a/Sources/Misc/StoreKitVersion.swift b/Sources/Misc/StoreKitVersion.swift
index c985082768..f5bf8a6195 100644
--- a/Sources/Misc/StoreKitVersion.swift
+++ b/Sources/Misc/StoreKitVersion.swift
@@ -59,6 +59,21 @@ extension StoreKitVersion {
         }
     }
 
+    /// - Returns: `true` if SK2 is available and usable when PurchasesAreCompleted==.myApp on this device
+    // swiftlint:disable:next identifier_name
+    var isStoreKit2EnabledAndAvailableWhenPurchasesAreCompletedByMyApp: Bool {
+        if #available(iOS 15.0, macOS 12.0, tvOS 15.0, watchOS 8.0, *) {
+            switch self {
+            case .storeKit1:
+                return false
+            case .storeKit2:
+                return true
+            }
+        } else {
+            return false
+        }
+    }
+
     /// - Returns: `true` if and only if SK2 is enabled and it's available.
     var isStoreKit2EnabledAndAvailable: Bool {
         switch self {
diff --git a/Sources/Purchasing/Purchases/Purchases.swift b/Sources/Purchasing/Purchases/Purchases.swift
index b4cef05fbb..82fb8c1bd1 100644
--- a/Sources/Purchasing/Purchases/Purchases.swift
+++ b/Sources/Purchasing/Purchases/Purchases.swift
@@ -332,13 +332,10 @@ public typealias StartPurchaseBlock = (@escaping PurchaseCompletedBlock) -> Void
             diagnosticsTracker: diagnosticsTracker
         )
 
-        let paymentQueueWrapper: EitherPaymentQueueWrapper = systemInfo.storeKitVersion.isStoreKit2EnabledAndAvailable
-            ? .right(.init())
-            : .left(.init(
-                operationDispatcher: operationDispatcher,
-                observerMode: observerMode,
-                sandboxEnvironmentDetector: systemInfo
-            ))
+        let paymentQueueWrapper = Purchases.buildPaymentQueueWrapper(
+            systemInfo: systemInfo,
+            operationDispatcher: operationDispatcher
+        )
 
         let offeringsFactory = OfferingsFactory()
         let receiptParser = PurchasesReceiptParser.default
@@ -685,6 +682,30 @@ public typealias StartPurchaseBlock = (@escaping PurchaseCompletedBlock) -> Void
         }
     }
 
+    private static func buildPaymentQueueWrapper(
+        systemInfo: SystemInfo,
+        operationDispatcher: OperationDispatcher
+    ) -> EitherPaymentQueueWrapper {
+        if systemInfo.observerMode &&
+            systemInfo.storeKitVersion.isStoreKit2EnabledAndAvailableWhenPurchasesAreCompletedByMyApp {
+            // On iOS 15, we allow developers to make purchases with SK2 when PurchasesAreCompletedBy==.myApp.
+            // We need to specifically check for this case because otherwise we use SK1 on iOS 15, and if
+            // We are on iOS 15 with PurchasesAreCompletedBy==.myApp and SK2, we need to only listen to purchases
+            // via SK2.
+            return .right(PaymentQueueWrapper())
+        }
+
+        let paymentQueueWrapper: EitherPaymentQueueWrapper = systemInfo.storeKitVersion.isStoreKit2EnabledAndAvailable
+            ? .right(.init())
+            : .left(.init(
+                operationDispatcher: operationDispatcher,
+                observerMode: systemInfo.observerMode,
+                sandboxEnvironmentDetector: systemInfo
+            ))
+
+        return paymentQueueWrapper
+    }
+
     /// - Parameter purchases: this is an `@autoclosure` to be able to clear the previous instance
     /// from memory before creating the new one.
     @discardableResult
diff --git a/Sources/Purchasing/Purchases/TransactionPoster.swift b/Sources/Purchasing/Purchases/TransactionPoster.swift
index 478dde946a..739418f1fc 100644
--- a/Sources/Purchasing/Purchases/TransactionPoster.swift
+++ b/Sources/Purchasing/Purchases/TransactionPoster.swift
@@ -257,30 +257,48 @@ private extension TransactionPoster {
 
     func fetchEncodedReceipt(transaction: StoreTransactionType,
                              completion: @escaping (Result<EncodedAppleReceipt, BackendError>) -> Void) {
-        if systemInfo.storeKitVersion.isStoreKit2EnabledAndAvailable,
-           let jwsRepresentation = transaction.jwsRepresentation {
-            if transaction.environment == .xcode, #available(iOS 15.0, tvOS 15.0, macOS 12.0, watchOS 8.0, *) {
+
+        func handleTransactionWithJWSRepresentation(jwsRepresentation: String) {
+            if transaction.environment == .xcode, #available(iOS 15.0, macOS 12.0, tvOS 15.0, watchOS 8.0, *) {
                 _ = Task<Void, Never> {
                     completion(.success(
-                        .sk2receipt(await self.transactionFetcher.fetchReceipt(containing: transaction))
-                    ))
+                        .sk2receipt(await self.transactionFetcher.fetchReceipt(containing: transaction)))
+                    )
                 }
             } else {
                 completion(.success(.jws(jwsRepresentation)))
             }
-        } else {
-            self.receiptFetcher.receiptData(
-                refreshPolicy: self.refreshRequestPolicy(forProductIdentifier: transaction.productIdentifier)
-            ) { receiptData, receiptURL in
-                if let receiptData = receiptData, !receiptData.isEmpty {
-                    completion(.success(.receipt(receiptData)))
-                } else {
-                    completion(.failure(BackendError.missingReceiptFile(receiptURL)))
-                }
+        }
+
+        if systemInfo.observerMode &&
+            systemInfo.storeKitVersion.isStoreKit2EnabledAndAvailableWhenPurchasesAreCompletedByMyApp,
+           let jwsRepresentation = transaction.jwsRepresentation {
+            // On iOS 15, we allow developers to make purchases with SK2 when PurchasesAreCompletedBy==.myApp.
+            // In this case, we should POST the SK2 receipt despite running on iOS 15, where we would normally
+            // POST a SK1 receipt if PurchasesAreCompletedBy==.revenueCat
+
+            handleTransactionWithJWSRepresentation(jwsRepresentation: jwsRepresentation)
+            return
+        }
+
+        if systemInfo.storeKitVersion.isStoreKit2EnabledAndAvailable,
+           let jwsRepresentation = transaction.jwsRepresentation {
+
+            handleTransactionWithJWSRepresentation(jwsRepresentation: jwsRepresentation)
+            return
+        }
+
+        // Fetch a SK1 receipt
+        self.receiptFetcher.receiptData(
+            refreshPolicy: self.refreshRequestPolicy(forProductIdentifier: transaction.productIdentifier)
+        ) { receiptData, receiptURL in
+            if let receiptData = receiptData, !receiptData.isEmpty {
+                completion(.success(.receipt(receiptData)))
+            } else {
+                completion(.failure(BackendError.missingReceiptFile(receiptURL)))
             }
         }
     }
-
 }
 
 // MARK: - Properties