Form 637 — no verified IRS fax number

There is no reliably published IRS fax number for Form 637 (Application for Registration for Certain Excise Tax Activities). The current instructions direct applicants to mail it to the Excise Operations Unit in Cincinnati.

Old fax numbers for Form 637 circulate online; sending your registration to a dead line silently delays activities that require an active registration number. Mail it with tracking, and expect IRS follow-up contact during the review.

Deadline

Register before engaging in the excise activity — reviews commonly take 60–120 days.

Frequently asked questions

No primary-source fax number is currently published. The instructions say to mail the application to the Cincinnati Excise Operations Unit — treat any fax number you find online as unverified.

Typically 60–120 days: the IRS reviews the application, may inspect or request documents, then issues the registration letter.
We haven't been able to verify a primary-source IRS fax number for Form 637, so we don't auto-send it — a fax to a wrong or dead line is worse than mail. The forms below fax today: 5472+1120, SS-4, 2553.