Method and apparatus for predicting a transaction's outcome in a transaction processing environment are provided. A transaction request is received by a transaction processing monitor (TPM), where the transaction request comprises a plurality of tags. The TPM identifies historical prior transactions corresponding to the transaction request, and determines a plurality of historical tags associated with those historical transactions. The TPM then determines whether a predicted execution time exceeds the transaction request's timeout, and proceeds accordingly. If the predicted execution time exceeds the timeout value, the transaction is immediately returned as failed. The tags associated with a given transaction request are repeatedly updated as the request traverses the transaction processing system, and the transaction is repeatedly verified to ensure that it can still be completed successfully.