LetterAgent
Mail physical letters by just asking your AI assistant.
Home > Guides > Fax to the IRS
Yes. IRS notices usually include a fax number, and the IRS accepts faxed responses to most correspondence audits and notices. Faxing beats mailing when a deadline is close: your fax confirmation page proves when the transmission completed. Keep the confirmation with a copy of everything you sent.
This is general information, not tax advice.
Yes, and faxing is more normal at the IRS than most people expect. Most IRS notices (the CP series letters about balances, audits, or missing documents) print a fax number right on the notice for sending your response. Tax professionals routinely fax responses to correspondence audits instead of mailing them. Use the fax number on your specific notice, not a general IRS number you find online: each number routes to the unit handling your case.
That routing is the part people miss. A mailed response goes through a central mailroom and gets sorted; a faxed response lands directly with the team working your notice. For time-sensitive responses, that direct routing can matter.
| Situation | Mailing | Faxing |
|---|---|---|
| Response deadline is days away | Risky: mail transit eats your window | Better: transmission completes the same day |
| Notice includes a fax number | Works, but slower | The number is there because they expect faxes |
| You need proof of timely sending | Certified mail receipt proves mailing date | Confirmation page proves transmission date and time |
| Sending original documents | Fine for originals you can replace | Sends images, so keep your originals |
In short: fax when the clock is ticking or you want timestamped proof of sending; mail when you have time and want the physical paper trail.
A short checklist covers it:
Keep a complete copy of everything you faxed, clipped to the confirmation page.
The confirmation page. It records the destination number, the page count, and the date and time the transmission finished. The IRS does not routinely send back a receipt acknowledging your fax, so the confirmation page plus your copies is your proof. If the IRS later says it never got your response, the confirmation page with the correct fax number is what you show.
Faxing is for correspondence and responses, not for everything. Do not fax your original tax return as a way of filing it: the IRS generally does not accept faxed original returns. Do not fax payments: payments go through the usual channels, by mail or electronic payment. And do not fax documents the notice did not ask for: unsolicited material can slow the review of your case.
If you would rather have the faxing handled for you, you can ask your AI assistant to send the fax through LetterAgent: the assistant verifies the page count, gives you a per-fax quote, you approve the exact total and pay once, and the fax goes to the US or Canadian number you name. Fax is currently in testing, so treat it as experimental for now.
Ready to fax it? Fax with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it is sent.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com