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Home > Guides > Safest way to mail a payment to the IRS
Use certified mail (or registered mail) so you get proof the IRS received your payment, and keep the receipt. Send a separate check for each form and tax period, make it payable to the United States Treasury, and write your Social Security number, tax year, and form number on the memo line. Mail to the address in that form's instructions.
This is general information, not tax advice.
Tax law has a rule sometimes called the mailbox rule: a document or payment that is properly addressed and mailed on time generally counts as filed or paid on the date it was mailed, not the date the IRS opens it. But the rule only helps you if you can prove when you mailed it. A certified mail receipt, with its postmark and tracking, is that proof. Registered mail works too and adds a chain of custody, though it costs more and moves slower.
This matters most near deadlines. If your payment arrives after April 15 but the certified receipt shows you mailed it on April 14, you have the evidence to defend the timeliness. Without proof of mailing, a lost envelope becomes a late payment, with penalties and interest attached.
| Mailing choice | What you get | When to use it |
|---|---|---|
| Certified mail | Proof of mailing with postmark plus delivery tracking and a delivery record | Payments near a deadline or large amounts |
| Registered mail | Chain of custody at every handoff, the strongest paper trail | Very large payments where you want maximum documentation |
| Regular First-Class mail | No proof of mailing and no delivery record | Small payments mailed well ahead of any deadline |
The memo line is small and it does the most work. Write your Social Security number, the tax year the payment is for, and the form or notice number it relates to. A check that says only "IRS" in the payee line and nothing in the memo can sit in a suspense file while someone figures out which account it belongs to. The payee should read the United States Treasury, not IRS and not Internal Revenue Service: that is the exact payee the instructions call for, and banks and processing centers expect it.
Send one check per form and per tax period. If you owe for two different years, or for a return balance and an estimated payment, those are two checks in two envelopes. Combining payments on one check is one of the most common reasons a payment gets applied to the wrong period, and untangling a misapplied payment takes far longer than writing a second check.
The IRS uses different processing centers for different forms, and the correct address also depends on your state and on whether a payment is enclosed. The instructions for the form you are paying with list the right address: use them, not an address from an old envelope or a different form's instructions. Double-check the ZIP code digit by digit. A payment mailed to the wrong center usually gets there eventually through internal forwarding, but "eventually" is not what you want near a deadline.
Four, in rough order of how painful they are to fix. First, mailing cash: the IRS says not to, and a lost cash envelope is simply gone. Second, an unsigned check: it cannot be deposited, and by the time it comes back to you the deadline may have passed. Third, the wrong payee or a blank memo line, which stalls processing. Fourth, forgetting to keep copies: photograph or photocopy the check, the form or voucher, and the mailing receipt before the envelope closes. If anything goes wrong later, that little packet of copies is your whole case.
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