How to Send Mail to the IRS: Address, Postmarks, and Proof Methods

To send mail to the IRS, use USPS Certified or Registered Mail, or one of the specific FedEx, UPS, or DHL services the IRS has designated, and address it to the processing center listed in your form’s instructions for your state and whether you’re enclosing a payment. Those methods give you a dated receipt that federal law treats as your filing date, even if delivery takes longer than expected.¹

Find the Right IRS Address First

There is no single mailing address for the IRS. The correct one depends on three things: which form you’re filing, the state you live in, and whether you’re enclosing a payment.² Each form’s instructions list the address, and the IRS keeps a searchable table online organized by state.³

Confirm the street address, city, and ZIP against the current instructions before you seal the envelope. Sending a return to the wrong processing center can significantly delay acknowledgment. One address caveat: if you’re mailing a payment with Form 1040-V, the IRS advises regular mail rather than a private carrier, because private carriers can delay payment processing.³

Why the Postmark Date Is Your Filing Date

Federal law treats a document mailed to the IRS as filed on the date it is postmarked, not the date the IRS actually receives it, as long as the envelope is properly addressed with prepaid postage and the postmark falls on or before the deadline.¹ This is the “postmark rule,” and it covers returns, payments, and most other documents the IRS requires.

Any class of U.S. mail qualifies, including regular first-class. The problem with plain first-class mail is proof: if the envelope is lost or the IRS says it never arrived, you have no way to show when (or whether) you mailed it. That’s why the methods below matter.

Methods That Give You Legal Proof

USPS Certified and Registered Mail

Certified Mail and Registered Mail get special treatment under the same statute. The registration or certification date is treated as the postmark date, and the receipt itself serves as legal proof that the document was delivered to the IRS.¹⁴ No other class of USPS mail gives you that presumption of delivery.

Certified Mail is the usual choice for individual taxpayers. You get a date-stamped receipt when you drop it off, and you can add a return receipt so someone at the IRS has to sign for it. Registered Mail provides a full chain-of-custody record and is generally used for high-value or sensitive documents.

IRS-Designated Private Delivery Services

FedEx, UPS, and DHL each offer specific services the IRS has approved for the postmark rule. Only those service levels qualify. If you use any other tier from the same carrier, your filing date is the day the IRS actually receives the package, not the day you shipped it.⁵ The current approved list:

DHL Express: DHL Express 9:00, DHL Express 10:30, DHL Express 12:00, DHL Express Worldwide, DHL Express Envelope, DHL Import Express 10:30, DHL Import Express 12:00, and DHL Import Express Worldwide
FedEx: FedEx First Overnight, FedEx Priority Overnight, FedEx Standard Overnight, FedEx 2 Day, FedEx International Next Flight Out, FedEx International Priority, FedEx International First, and FedEx International Economy
UPS: UPS Next Day Air Early A.M., UPS Next Day Air, UPS Next Day Air Saver, UPS 2nd Day Air, UPS 2nd Day Air A.M., UPS Worldwide Express Plus, and UPS Worldwide Express

Ask the carrier for written proof of the mailing date, and keep it with your tax records.⁵ FedEx Ground, UPS Ground, and USPS Priority Mail are not on the approved list. Using them near a deadline risks a late-filing determination if the package moves slower than expected.

Preparing the Envelope

Every return, statement, or document you send must include your taxpayer identification number, typically your Social Security Number or, if you don’t have one, your Individual Taxpayer Identification Number.⁶ Leaving it off can delay processing and trigger penalties.⁷

Sign the return. A tax return is not legally filed until you sign it under penalty of perjury, and an unsigned return can expose you to failure-to-file penalties.⁸⁹ The current forms are on the IRS website.¹⁰

For a Form 1040, attach copies of your W-2s and any Forms 1099-R (if tax was withheld) to the front. Place schedules and additional forms behind the 1040 in order of the “Attachment Sequence Number” printed in the upper-right corner of each form. Supporting statements go last, arranged to match the schedules they relate to.

If you owe tax, make the check or money order payable to “U.S. Treasury” and write your Social Security Number (or ITIN), the tax year, and the form number on the payment so it can be credited correctly.¹¹ Don’t staple or clip the payment to the return. Fill out Form 1040-V and enclose the voucher and payment loosely in the envelope with your return.

Deadline Falls on a Weekend, Holiday, or You’re Abroad

If the last day to file or pay falls on a Saturday, Sunday, or legal holiday, the deadline moves to the next business day.¹² “Legal holiday” means a holiday recognized in the District of Columbia, plus any statewide holiday in the state where the IRS office you’re filing with is located. The filing deadline for individual returns for the 2026 tax year is April 15, 2026.¹³

Mailing from abroad works the same way: a return postmarked in a foreign country, or shipped by a designated private delivery service on or before the due date, is considered timely when it reaches the IRS.¹⁴ U.S. citizens and resident aliens living overseas automatically get a two-month extension (to June 15 for calendar-year filers), though interest on any balance owed still accrues from the original April deadline. Hold on to your proof of international postage.

What It Costs If the Mailing Is Late

Picking the wrong delivery method, or missing the deadline entirely, can trigger two separate penalties that stack.

Failure to file: 5% of the unpaid tax for each month or partial month the return is late, capped at 25%. If your return is more than 60 days late, the minimum penalty is the lesser of $525 or the full amount of tax you owe.¹⁵¹⁶
Failure to pay: 0.5% of the unpaid tax for each month the balance is outstanding, also capped at 25%. The rate drops to 0.25% for any month an installment agreement is in effect and rises to 1% once the IRS issues a notice of intent to levy.¹⁵¹⁶

When both apply in the same month, the failure-to-file penalty is reduced by the failure-to-pay amount, so the combined charge is no more than 5% per month for up to five months. After five months the filing penalty maxes out, but the payment penalty keeps accruing. The combined ceiling is 47.5% of the unpaid tax. Filing the return, even without full payment, stops the more expensive filing penalty from growing.

Confirming the IRS Got It

If you enclosed a payment, a cashed check or money order is your earliest sign the mailing arrived. You can also log in to the IRS Online Account portal to see transcripts, payment history, and your balance.¹⁷ Expecting a refund? Your status should show up in the “Where’s My Refund?” tool about four weeks after you mail a paper return.¹⁸

If the IRS Says It Never Received Your Mailing

Your next step depends on what proof you kept. A Certified or Registered Mail receipt is legal evidence of both the mailing date and delivery; present it to resolve the dispute. Written proof from a designated private delivery service works the same way.¹

If you mailed the document with no tracking, proving timely filing gets much harder, and you’ll usually need to refile. Send the replacement by Certified Mail or a designated private carrier, and keep copies of everything. If you were due a refund or owed nothing, refiling late doesn’t produce a penalty, because failure-to-file and failure-to-pay penalties only apply when a balance is due.¹⁵ If you did owe, penalties and interest may apply from the original due date, and you may need to request penalty abatement by showing reasonable cause.

1
Office of the Law Revision Counsel. 26 USC 7502 Timely Mailing Treated as Timely Filing and Paying
2
Internal Revenue Service. Where to File Paper Tax Returns With or Without a Payment
3
Internal Revenue Service. Where to File Addresses for Taxpayers and Tax Professionals Filing Form 1040 or Form 1040-SR
4
Internal Revenue Service. Memorandum on USPS Delivery Confirmation
5
Internal Revenue Service. Private Delivery Services (PDS)
6
Office of the Law Revision Counsel. 26 USC 6109 Identifying Numbers
7
eCFR. 26 CFR 301.6109-1 Identifying Numbers
8
Internal Revenue Service. Memorandum on Photocopied Signatures on Amended Returns
9
Internal Revenue Service. Failure To File/Failure To Pay Penalties
10
Internal Revenue Service. Forms, Instructions and Publications
11
Internal Revenue Service. Pay by Check or Money Order
12
Office of the Law Revision Counsel. 26 U.S. Code 7503 – Time for Performance of Acts Where Last Day Falls on Saturday, Sunday, or Legal Holiday
13
Internal Revenue Service. When to File
14
Internal Revenue Service. Extensions
15
Office of the Law Revision Counsel. 26 USC 6651 Failure to File Tax Return or to Pay Tax
16
Internal Revenue Service. Topic No. 653, IRS Notices and Bills, Penalties and Interest Charges
17
Internal Revenue Service. Get Your Tax Records and Transcripts
18
Internal Revenue Service. Where’s My Refund?