We recently acquired a bank and their routing number and had the regional ACH payment association complete our annual ACH compliance audit. At the exit of the audit, they mentioned that we needed to also have an audit of the acquired routing number and that they only completed an audit of our primary routing number. Has anyone heard of this? Do you have any information on where in the rules I could find this?

Thanks for your help!

I have never heard of this.

I have heard that all routing numbers must be reviewed (but I will admit that I do not recall where it came from)

Audit requirement are spelled out in appendix 8 of the NACH operating rules (IF an NACH member) I do not have access to it.