Measured from real faxes — updated weekly
How long does the IRS take to fax back your EIN?
Typical (median) time the IRS took to fax back
arrived within 3 weeks
slowest confirmation we observed
Based on real EIN confirmations the IRS faxed back to FaxTerra users · updated June 30, 2026
How long replies actually took
Share of EIN confirmations received in each time window.
What to expect after you fax Form SS-4
A few practical notes, based on how the fax-back process actually works.
The IRS faxes the EIN back to your cover-sheet number
When you apply by fax, the IRS sends your EIN assignment back to the return fax number on your cover sheet — usually within about two weeks, as the data above shows.
Keep that fax number reachable until the reply arrives
A minority of confirmations take longer than a month. If the return number is disconnected by the time the IRS replies, the fax has nowhere to land — so keep the number you listed active until you have the EIN in hand.
No reply after ~4 weeks? Call for a 147C letter
You can call the IRS Business & Specialty Tax Line at (800) 829-4933 (Mon–Fri, 7am–7pm local time) and request a Letter 147C, which verifies your EIN. They can fax it to you during the call.
The mailed CP-575 is separate
The official CP-575 confirmation letter also arrives by mail, typically 4–6 weeks after your EIN is assigned. Keep both the fax-back (for immediate use) and the CP-575 (for your records).
Official IRS reference: Where to File Form SS-4 · Get an EIN
These are real, anonymized timings measured by FaxTerra: the gap between a user faxing Form SS-4 (EIN application) to the IRS and the IRS faxing the EIN confirmation back (observed arriving from IRS lines in Memphis, TN and West Virginia). To avoid skewing the numbers toward fast replies, we only count applications faxed at least 30 days ago — long enough for the reply window to have largely completed. This is directional — not an official IRS service-level figure. Last updated June 30, 2026.