By Michael Chen · Published August 21, 2025 · Updated March 9, 2026 · 4 min read
It’s 2025, and while we’re talking about AI and space travel, the IRS still runs on fax machines. If you've ever tried calling them, you know that "hold music" is a dark place. Sending a fax is often the only way to get your documents into the hands of an agent without waiting weeks for the USPS to deliver a letter.
But here is the catch: you don't actually need to find a dusty fax machine at FedEx or Staples. You can handle your IRS filings directly from your phone or laptop.
Below is the verified, up-to-date list of IRS fax numbers for 2026.
Pro Tip for Business Owners
If you are in a rush, mFax.to allows you to upload a PDF and send it to these numbers in under 60 seconds. No subscription, no headache.
1. Form SS-4 (Applying for an EIN)
If the online EIN assistant is giving you the "Technical Difficulties" error (which happens more often than it should), faxing your SS-4 is the fastest backup.
EIN Application
Form SS-42. Form 2553 (S-Corp Election)
Timely filing is critical for S-Corp status. Missing the 75-day window can lead to a long "late election relief" process. Note that the number depends on where your business is based.
S-Corp Election
Form 25533. Form 2848 & 8821 (Power of Attorney)
These are handled by the CAF (Centralized Authorization File) units. If you are a tax pro or an individual granting authority to an accountant, use these numbers:
Power of Attorney / CAF
Form 2848 / 88214. Form 4506-T (Tax Transcripts)
Mortgage lenders often ask for these. While the "Get Transcript" tool on the IRS website is faster, some older records require a faxed request.
Transcript Requests
Form 4506-TCan I Fax My 1040 Tax Return?
The short answer is No.
The IRS does not accept original individual tax returns (1040) via fax. You must either e-file or mail them.
The only exception: If you receive a notice (like a CP2000) or are under audit, your assigned agent might give you a direct fax number to send documents. In that case, always use the specific number they provide you, not the general ones listed above.
How to Fax the IRS with mFax.to
When you're dealing with the IRS, "lost in the mail" is a nightmare. Online faxing gives you a digital paper trail.
1. Prepare Your Document
The IRS still requires wet ink signatures for most forms.
- Print the form.
- Sign it with a pen.
- Use a scanning app (or mFax.to’s mobile interface) to create a high-contrast, black-and-white PDF.
2. Add a Professional Cover Sheet
The IRS processes millions of faxes. Without a cover sheet, yours might end up in the "mystery pile." Include: * Your Name/Business Name.
- Your Taxpayer ID (EIN or SSN).
- The Form Number (e.g., "ATTN: Form 2553").
- Total page count.
3. Send and Secure Your Receipt
Go to mFax.to, upload your file, and enter the IRS number. Once the transmission is complete, download the receipt. This receipt contains the "OK" status and a timestamp—this is your "Get Out of Jail Free" card if the IRS claims you missed a deadline.
Why use mFax.to for Taxes?
- Privacy First: We don't store your documents longer than necessary.
- Zero Hardware: No need to buy a fax machine or a phone line.
- IRS Ready: High-resolution transmission ensures the IRS's scanners can actually read your handwriting.
Related Guides
For more detailed help with specific forms:
- How to fax Form 2553 (S-Corp election) — step-by-step with fax numbers by state
- Faxing IRS Form 4506-T — for tax transcripts with state-by-state lookup tool
- How to fax IRS Form 2848 — Power of Attorney guide
Final Checklist Before You Hit Send
- Did you sign the form? (Most common reason for rejection).
- Is the PDF clear and not blurry?
- Did you use the correct number for your specific state?
- Do you have your mFax.to confirmation receipt saved?
Need to send your form right now? Click here to start faxing securely with mFax.to.