IRS Form 637 (Application for Registration for Certain Excise Tax Activities) Fax Number

Activity Letters identify which specific excise-tax activity you're registering for, such as M for blending gasoline, diesel, or kerosene, or V for exporting ozone-depleting chemicals. The current form lists 31 active Activity Letters, and you can register for more than one on a single Form 637 if you engage in multiple qualifying activities.

The IRS doesn't publish a fixed timeframe. Your application is reviewed before any registration takes effect, and the review can include an unannounced inspection of your business premises during normal business hours. Once approved, you'll receive a Letter of Registration, a copy of Form 637 itself is not proof of registration.

If you're required to register and don't, the IRS penalty is $10,000 for the initial failure, plus $1,000 for each additional day you remain unregistered, unless the failure is due to reasonable cause. You can check whether a business currently holds a valid registration using the IRS's online Form 637 status tool.

No fixed expiration. Once you hold an active Certificate of Registry or Letter of Registration, you don't need to reapply unless the IRS asks you to. You do need to notify the IRS within 10 days of any change to the information you submitted, and fuel registrants under section 4101 must reregister if more than 50% of the business's ownership changes hands.

Yes, they're separate obligations. Form 637 registers you for an excise-tax activity or exemption, it doesn't replace your ongoing tax filings. If you're liable for excise tax, you still file Form 720, the Quarterly Federal Excise Tax Return, on its normal schedule, Form 637 itself asks whether you already file or expect to file Form 720.