Go to any Post Office location. Take cash, a debit card, or a traveler's check.Pay for the money order using cash, debit card, or a traveler's check. Locations like the USPS won't let you pay for a money order with a check or credit card. How to fill out a money order. Fill in the name of the payee. Fill out the money order immediately and completely, leaving nothing blank. How do I activate my debit card? Here you will find answers to frequently asked questions regarding the Massachusetts Department of Revenue's (DOR) Collections process. Payment Information.