Check the mailing address for your tax return on the IRS website or your state tax agency website
Use the correct envelope size and place the tax return documents inside
Include all required forms, schedules, and attachments
Sign and date the return before mailing
Include payment if you owe taxes, using the approved payment voucher if required
Make a copy of the entire tax return for your records
Use sufficient postage based on the envelope weight
Mail the return by certified mail, return receipt, or another trackable method
Keep the mailing receipt and tracking number
Mail the return by the tax deadline or as soon as possible if filing late