Tools for adjusting a debit transaction, which can allow a payee to adjust the amount of the transaction without having to provide cash back to the payor. Instead, the refund amount may be applied as a credit against the debit transaction. In an aspect, the credit may be for any amount up to the original amount of the check (less any credit already applied). Optionally, one or more security and/or anti-fraud measures may be implemented, e.g., ensuring that the check is not subject to a collection proceeding and/or ensuring that the requested credit is not more than the amount of the check itself).