Is there any issue providing the C5A notice to business account holders who get a returned substitute check?

229.57 applies to consumers. If you provide the C5A notice referenced in this section to business account holders, it probably won't hurt as long you do what the disclosure says you will do (and provide the customer the rights the disclosure says they have). That said, this is more of a legal question (contract issue) than a compliance question so you may want to run it by legal counsel.