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Form 637: Application for Registration (For Certain Excise Tax Activities)
IRS Form 637 is an Application for Registration (For Certain Excise Tax Activities) that allows applicants to register with the IRS. The penalty for initial failure to register is $10,000.
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IRS Form 637 - Application for Registration (For Certain Excise Tax Activities)
IRS Form 637 is an Application for Registration (For Certain Excise Tax Activities) that allows applicants to register with the IRS. The penalty for initial failure to register is $10,000.
Risk Radar
Scan points- 1Ensure you correctly select the Activity Letter (X, S, M, etc.) for your specific excise tax activities.
- 2Filing without listing all current business operation addresses in Part III, Line 4.
- 3Not attaching the required additional information for each listed activity in Part II.
- 4Omitting the Activity Letter designation when applying for registration.
- 5Failing to list related entities and their ownership percentage (Part III, Line 3).
Plain English
This form lets a business or individual officially register with the Internal Revenue Service so they can properly handle excise taxes on specific activities. By filing Form 637, the applicant establishes their status with the IRS and lists exactly what kind of tax activity they will be performing. This registration is required for several types of operations, such as producing fuel or operating a pipeline.
Submission Date
- Filing date: 2026-01-08 11:11:06
- Preparation window: collect IDs, supporting records, and signatures in advance.
- Final review: verify names, dates, and required fields before submission.
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What this form is for
- Use this form when applying for excise tax registration for activities under sections 4101, 4222, 4662, and 4682.
- Do not use it when you are simply confirming an existing registration status; in that case, check https://apps.irs.gov/app/exciseTax/.
- Check Pub. 510, Excise Taxes instead when needing more general information regarding registrations.
Form selector
Use this form or another form?
Pipeline operator or vessel operator
Activity letter X applies for registration.
✓ Ensure you select the correct activity letter on Part II.
Blenders
Activity letter M applies for registration.
✓ Confirm if your business unit requires a separate EIN, as it is treated as a separate person.
Producers of clean transportation fuel that is SAF
Activity letter CA applies for registration due to the Inflation Reduction Act of 2022 (IRA22).
✓ Verify this activity letter matches your product type before completing Part II.
Deadline or filing window
The form applies for registration related to various excise tax sections and does not list a fixed due date. However, if an applicant fails to register when required, the penalty starts immediately at $10,000. No extension period is mentioned in the source text.
Checklist
What you need before filling it out
Application Purpose
Excise tax registration for activities under sections 4101, 4222, 4662, and 4682 · Form p.6 (General Instructions)
Initial Penalty Amount
$10,000 · Form p.6 (Penalty)
Required Mailing Address
Excise Operations Unit—Form 637 Mail Stop 5701G, Cincinnati, OH 45999 · Form p.6 (Mailing Address block)
Fuel Activity Questions
Checkboxes for questions 9 and 10 on page 2 · Form p.2 (Section C—For Certain Fuel Applicants)
Change Notification Window
Notify the IRS office within 10 days if any information changes · Form p.7 (Changes in Registration)
Fuel Activity Letter SA
Activity letter related to Section 40B SAF credit sold/used post-2022 and pre-Jan 1, 2025 · Form p.6 (What’s New)
Before you submit
- 1Verify the revision date on the form reads December 2025.
- 2Ensure Part I includes the correct Legal name of entity and its EIN.
- 3Confirm all required activities are listed or selected in Part II.
- 4If applying for fuel activities, answer questions 9 and 10 by checking 'Yes' or 'No'.
- 5If answering 'Yes' to any question on page 2, provide a full explanation.
- 6If listing articles for export/resale, ensure you list the businesses to which you intend to sell them (on page 2).
- 7Write your name and EIN clearly on every additional sheet attached.
How to file this form
- 1Complete all sections of IRS Form 637, including Part I identification details and Part II activity information.
- 2If applicable, answer the questions under Section C (Fuel Applicants) by checking 'Yes' or 'No', providing detailed explanations for any affirmative answers on page 2.
- 3Attach additional sheets if necessary, ensuring you write your name and EIN on each sheet.
- 4Sign the form and all attached sheets before mailing it to the IRS Excise Operations Unit at Mail Stop 5701G in Cincinnati, OH 45999.
Known limitations
- 1The purpose of Form 637 is to apply for excise tax registration for activities under sections 4101, 4222, 4662, and 4682.
- 2Each business unit that has, or is required to have, a separate Employer Identification Number (EIN) must be treated as a separate person when filing Form 637.
- 3The penalty for failure to register applies unless the failure is due to reasonable cause.
- 4If an applicant does not have an EIN, they may apply for one online at www.irs.gov/EIN or by mailing/faxing Form SS-4.
Field map
Compact field-by-field guide
General Info
2 items
Full legal name and taxpayer identification number (SSN or EIN).
Current mailing address.
Details
2 items
Complete all applicable sections of this form according to the official IRS instructions.
Enter the relevant dollar amount if this form involves tax calculation.
Certification
1 items
Read and acknowledge any certifications required by this form.
Signatures
1 items
Sign and date. Unsigned forms cannot be processed.
Almost done reviewing the fields?
Fillable formOpen in Editor->The current edition of IRS Form 637 is Revision December 2025; users can go to www.irs.gov/Form637 for the latest information, which includes updates such as activity letters CA and CN related to the Inflation Reduction Act of 2022.
What changed or needs a fresh check
- Edition date — confirm the revision reads December 2025.
- Fee — The penalty for initial failure to register is $10,000; no specific filing fee amount is listed in the source.
- Mailing address — use Excise Operations Unit—Form 637 Mail Stop 5701G, Cincinnati, OH 45999.
- Signature — Signatures are required, and you must write your name and EIN on any attached sheets.
- Activity Letter — confirm the correct letter (e.g., X for Pipeline operator) is selected or listed.
Quick Facts
Downloads
After you file
- 1A person with authority to bind the applicant must sign Form 637 before submission.
- 2The applicant must keep a copy of Form 637 after filing it.
- 3If additional sheets are used for explanations, the name and EIN must be written on each attached sheet.
- 4For registration relating to Taxable fuel, the regulations section 48.4101-1 applies.
- 5For registration relating to Exports of ozone-depleting chemicals, regulations section 52.4682-5 applies.
Sources
- SRCInstructions p.1 — Part I requires listing the Legal name of entity or individual and their Employer identification number (EIN).
- SRCInstructions p.1 — Form 637 must include fields for Trade name, Telephone number, Mailing address, Fax number, and City/state/country/ZIP.
- SRCInstructions p.6 — The purpose of Form 637 is to apply for excise tax registration for activities under sections 4101, 4222, 4662, and 4682.
- SRCInstructions p.6 — Pipeline or vessel operators must use activity letter X; Enterers, position holders, refiners, and terminal operators must use S.
- SRCInstructions p.6 — The penalty for initial failure to register is $10,000, followed by $1,000 per day after that, unless reasonable cause exists.
- SRCInstructions p.7 — Form 637 can be submitted with additional information relating to Taxable fuel (Reg. section 48.4101-1) or Exports of ozone-depleting chemicals (Reg. section 52.4682-5).
Common confusion points
Who must sign Form 637 if the applicant is an LLC?
A person that complies with the federal tax treatment of the LLC must sign it
→ Check the signature block on Form 637.
What happens if my street address and mailing address are different?
The filer must list their street address (including city, state/province, country, and ZIP/foreign postal code) in addition to the mailing address.
→ Review Part I of Form 637.
Which activity letter applies if you produce clean transportation fuel that is SAF?
Activity letter CA applies for producers of clean transportation fuel that is SAF.
→ Check the list on Page 6, under 'What's New'.
If my business unit has a separate EIN, does it need its own Form 637?
Yes; each business unit that has, or is required to have, a separate EIN is treated as a separate person.
→ Read the General Instructions on Page 6.
What is the penalty if you forget to register for an excise tax activity?
The initial failure incurs a $10,000 penalty, and $1,000 for each subsequent day of failure.
→ Review the Penalty section on Form 637.
Where should I send Form 637 instead of using the general address listed?
The filer must see 'Where To Apply' (a section earlier in the form) to determine the correct submission location, rather than sending it to the IRS Tax Forms and Publications address.
→ Check the final paragraph on Page 7.
Workflow map
Related forms and next steps
Current
After
Often used with
⚠ If something goes wrong
- If an applicant needs more information on registration details (e.g., Taxable chemicals), they should see sections 4662(c)(2) and 4662(b)(10).
Questions about IRS Form 637
What is IRS Form 637 used for?
This form lets a business or individual officially register with the Internal Revenue Service so they can properly handle excise taxes on specific activities. By filing Form 637, the applicant establishes their status with the IRS and lists exactly what kind of tax activity they will be performing. This registration is required for several types of operations, such as producing fuel or operating a pipeline.
Who must file IRS Form 637?
The following persons must register using Form 637: Pipeline operator or vessel operator (activity letter X), Enterers, position holders, refiners, and terminal operators (activity letter S), Blenders (activity letter M), Producers or importers of alcohol, agri-biodiesel, and biodiesel (letters AF, AB, NB), Producers of clean transportation fuel that is SAF (letter CA), Producers of clean transportation fuel that isn’t SAF (letter CN), and Producers or importers of SAF (letter SA) or second generation biofuel (letter SB).
What information does IRS Form 637 require?
Part I identifies the applicant's basic information; Part II requires listing specific activities with corresponding letters and descriptions; and Part III collects general details, such as whether Form 720 will be filed and business start dates.
When is IRS Form 637 due?
The form itself does not specify a filing deadline, but it applies for registration related to excise tax activities under sections 4101, 4222, 4662, and 4682. The penalty applies immediately upon failure to register if required.
Where do I file IRS Form 637?
Form 637 must be mailed to the IRS Excise Operations Unit at Mail Stop 5701G in Cincinnati, OH 45999. Applicants should also check www.irs.gov/Form637 for online submission options.
How do I complete IRS Form 637?
First, complete all sections of Form 637. Applicants must list their name and EIN on any attached sheets before submitting them. Finally, the applicant must enter the activity letter from the chart below the signature area to specify the registration purpose.
What happens if IRS Form 637 is filed incorrectly?
The penalty for failure to register is $10,000 for the initial failure, and it increases by $1,000 for each day following that failure unless reasonable cause is proven.
Who must sign Form 637 if the applicant is an LLC?
A person that complies with the federal tax treatment of the LLC must sign it Check the signature block on Form 637.
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