You must send it to International Registration Bureau, PO Box 2850, Albany, NY, 12220-0850.
How to get a refund from the New York state portion of the IRP registration fees I paid to other jurisdictions?
You may request that refound only if the other jurisdiction made an error and the error is on your invoice and/or you paid duplicate apportioned registration fees for the same vehicle.
One of my apportioned plates was stolen, what should I do?