Fill in the recipient and your address; for bills, include an account number; sign it; keep proof of payment. Take your money order receipt to any Post Office facility.Write bill number on check or money order. Mecklenburg County Tax Collector P.O. Box 71063. When filling out a money order, you'll need some basic information, such as the recipient's name and your address. Do not send cash through the mail. Generally, any financial institution, such as a bank or credit union, will have money orders, or you can go to a U.S. post office. If not, consider ordering a birth, death or marriage certificate from the Register of Deeds in the county of the event.