If you did not transmit your return, you never filed. You need to complete that process now. If you file a late return, the IRS will only pay interest if they don't pay the refund within 45 days of the actual filing date.
If you did file your return on time, and the IRS has delayed payment for some reason, they will pay interest starting 45 days after the April 15 filing deadline.
If you filed your return, the IRS paid a refund, then it depends on how you wanted your refund:
- If you asked for direct deposit but used the wrong account number, and it was paid, then it is over. the IRS did what you asked, and you have to talk to the person who owns the bank account you used.
- If you asked for direct deposit but used the wrong account number, and the refund was rejected, the IRS should have mailed a check to the address on your check return. If the check was lost or stolen from the mail you will have to start a trace. I don't know if the IRS will pay interest if they reissue the check.
- If you asked for your refund on a money card, contact the card issuing bank.
- If you asked for your fees to be deducted from your refund, the processing bank should have contacted you if they could not verify the account. They may have sent the refund back to the IRS for re-issue. Start by contacting the processing bank, then contact the IRS to run a trace.
