Publication 537 (2021), Installment Sales | Internal Revenue Service You can send us comments through IRS.gov/FormComments. Or, you can write to the Internal Revenue Service, Tax Forms and Publications, 1111 Constitution Ave. NW, IR-6526, Washington, DC 20224. Although we can’t respond individually to each comment received, we do appreciate your feedback and will consider your comments and suggestions as we revise our tax forms, …