A Globally Unique IDentifier (GUID) is used to match an authorization request with an authorization response for a transaction between a merchant and a consumer upon an account within a payment processing system where the payment amount is unknown until after the merchant receives the authorization response that includes the GUID. After receiving the authorization response and when the payment amount is known, the merchant forms a transmission that has information for delivery to an issuer of the account. This information is sufficient for the issuer to forward the payment amount from the account to pay the merchant for the transaction. While including the GUID and the payment amount, the information does not include an identifier of the account.