ACH Error Code R55 - What is this?

ACH code R55 refers to a notification of an incorrect routing number used for an Automated Clearing House (ACH) transaction.
Routing numbers are nine-digit numbers identifying banks and financial institutions in the United States. ACH transactions use routing numbers to identify the bank holding the debited or credited account.
If an incorrect routing number is used for an ACH transaction, the transaction may be rejected or delayed, and the receiving bank may charge a fee for processing the transaction.

If you receive an ACH code R55 notification, you should contact the originator of the transaction to correct the routing number and reprocess the transaction with the correct information.