The NACHA Operating Rules provide a means of identifying business checks that are ineligible for check conversion, and also allow businesses to take steps to prevent their checks from being converted.

Checks with an Auxiliary On-Us field in the MICR line are ineligible for electronic conversion. Businesses that want to opt out of all forms of check conversion can use checks that include the Auxiliary On-Us field.

Learn more about identifying business checks ineligible for conversion »

The Rule in Brief

The NACHA Operating Rules limit the conversion of consumer or business checks to items of $25,000 or less, and also:

• Assist businesses and financial institutions in identifying which checks are eligible for conversion under ARC, POP, and BOC.
• Allow businesses to take steps to prevent their check from being converted at a point-of-purchase, at a lockbox, or at a dropbox.
• Include a Return Reason Code (R39) so financial institutions can return ineligible items that are converted under ARC, POP, and BOC.