diff --git a/modules/sdk-core/src/bitgo/baseCoin/iBaseCoin.ts b/modules/sdk-core/src/bitgo/baseCoin/iBaseCoin.ts
index 5d3c2b96cc..86e8d9ffb6 100644
--- a/modules/sdk-core/src/bitgo/baseCoin/iBaseCoin.ts
+++ b/modules/sdk-core/src/bitgo/baseCoin/iBaseCoin.ts
@@ -277,8 +277,14 @@ export interface ParseTransactionOptions {
   [index: string]: unknown;
 }
 
-// TODO (SDKT-9): reverse engineer and add options
+/**
+ * This is only used for determining the PayGo fee of a transaction which is only relevant for UTXO coins.
+ * Some coins return various other fields here, but they are only used internally by the respective coins.
+ */
 export interface ParsedTransaction {
+  // the callsite assumes that this is the PayGo amount
+  implicitExternalSpendAmount?: number | bigint;
+  // coins may add internal fields
   [index: string]: unknown;
 }
 
diff --git a/modules/sdk-core/src/bitgo/pendingApproval/pendingApproval.ts b/modules/sdk-core/src/bitgo/pendingApproval/pendingApproval.ts
index 6b903fcaf8..ebf7e898ff 100644
--- a/modules/sdk-core/src/bitgo/pendingApproval/pendingApproval.ts
+++ b/modules/sdk-core/src/bitgo/pendingApproval/pendingApproval.ts
@@ -304,16 +304,16 @@ export class PendingApproval implements IPendingApproval {
     prebuildParams = _.extend({}, prebuildParams, { reqId: reqId });
     const signedTransaction = await this.wallet.prebuildAndSignTransaction(prebuildParams);
     // compare PAYGo fees
-    const originalParsedTransaction = (await this.baseCoin.parseTransaction({
+    const originalParsedTransaction = await this.baseCoin.parseTransaction({
       txParams: prebuildParams,
       wallet: this.wallet,
       txPrebuild: originalPrebuild,
-    })) as any;
-    const recreatedParsedTransaction = (await this.baseCoin.parseTransaction({
+    });
+    const recreatedParsedTransaction = await this.baseCoin.parseTransaction({
       txParams: prebuildParams,
       wallet: this.wallet,
       txPrebuild: signedTransaction,
-    })) as any;
+    });
 
     if (_.isUndefined(recreatedParsedTransaction.implicitExternalSpendAmount)) {
       return signedTransaction;