For letter, learn the format properly and write in the stipulated word limit provided. How to apply for assistance on your water bill based on income, age, or a special situation that is making it hard to pay your water bill.Use USPS PO Boxes for business or personal use. Learn how to reserve, rent, renew, and manage a PO Box online, as well as how much a PO Box costs. Go through the sample essays so that you will get an idea. General Recommendations. If you would like to use a check, make sure it has your name and address pre-printed in the top left corner. The notice explains proposed changes to your tax return and information we used to determine them. This notice isn't a bill and your response may be required. You can fill out a LOOP application and mail it to: Philadelphia Department of Revenue P.O. Box 53250.