The AQ modifier is used when the address of the location the services were rendered has a HPSA geographic designation but the ZIP code is not allowed for automatic payment. Eligibility is determined by designation as of Dec 31 of the prior year. For example: If your address became designated within 2018, you would append the AQ modifier on claims with DOS in 2019.

Additional information is located at Health Professional Shortage Area (HPSA).