How to Get an EIN Number in New Mexico for Free

You can get an EIN for a New Mexico business for free by applying directly with the IRS. The online application at irs.gov takes about ten minutes and returns your nine-digit number on screen the moment it validates. Fax and mail are available too, and none of the three costs a cent.¹ After the federal EIN is issued, most New Mexico businesses also need a separate state Business Tax Identification Number from the Taxation and Revenue Department.²

Do You Actually Need an EIN

The IRS requires an EIN when you hire employees, operate as a partnership or corporation, pay excise taxes, or administer certain trusts and retirement plans.¹ An LLC with two or more members is treated as a partnership and needs one. A corporation needs one whether or not it has employees.

A single-member LLC is the interesting case. If you are the sole owner, have no employees, and owe no excise taxes, the IRS does not require your LLC to have its own EIN, and you can use your personal Social Security Number for federal tax purposes.³ In practice, most banks will not open a business account without an EIN, so plenty of single-member LLCs apply voluntarily. The IRS allows that.

Apply Only Through the IRS. It Is Free

The IRS charges nothing for an EIN. If a website is asking for a fee, you are not on the IRS website. In April 2025 the FTC warned about third-party sites charging up to $300 for the same service, using IRS-style logos and putting “IRS” in their domain names to look official.⁴ The real application lives at irs.gov/ein. If the URL in your browser does not end in .gov, close the tab.

What to Have Ready Before You Start

Gathering this ahead of time keeps the online session from timing out and prevents rework on a paper filing:

The exact legal name of your entity, matching what you filed with the New Mexico Secretary of State.
Your entity type: sole proprietorship, partnership, LLC, corporation, or nonprofit.
The responsible party. This is one individual who owns, controls, or manages the entity’s funds and assets. For a corporation this is usually the principal officer; for a partnership, the general partner; for a trust, the grantor or trustor. It must be a person, not another entity, with the sole exception of government agencies.⁵
The responsible party’s Social Security Number or Individual Taxpayer Identification Number.⁶
A physical street address. A P.O. box works for your mailing address, but the IRS does not allow one in the separate street-address field.⁷
Your reason for applying (starting a new business, hiring employees, banking, and so on).
The date the business started or was acquired. For a New Mexico LLC or corporation, use the date the Secretary of State approved your formation documents.

For LLCs specifically, the number of members matters. A single-member LLC defaults to a disregarded entity for tax purposes; a multi-member LLC defaults to a partnership. Getting the count wrong on the application creates real headaches at tax time.⁸

The Three Ways to Apply

Online

The online application is the fastest option. It is available Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern, Saturday from 6:00 a.m. to 9:00 p.m. Eastern, and Sunday from 6:00 p.m. to midnight Eastern.¹ The IRS walks you through each field in a web interview, and if your information validates, your EIN appears on screen along with a downloadable CP 575 confirmation notice.

Download or print the CP 575 immediately. The IRS does not let you return to retrieve it later, and a replacement 147C verification letter typically cannot be issued for roughly 30 days after a new EIN is assigned.⁹ It sounds like a small mistake right up until it stalls a bank account opening.

Fax

Complete Form SS-4, sign it, and fax it to 855-641-6935.¹⁰ The IRS typically faxes your EIN back within four business days.

Mail

Mail the signed Form SS-4 to:

Internal Revenue Service
Attn: EIN Operation
Cincinnati, OH 45999¹⁰

Expect the EIN to arrive by mail in about four weeks. To check on a mailed application, call 800-829-4933.⁷

One EIN Per Day

Whatever method you use, the IRS caps issuance at one EIN per responsible party per day.¹¹ If you are forming multiple New Mexico entities at once, plan the applications across separate days.

After the EIN Is Issued

Your EIN is valid the moment the IRS assigns it, but there is a lag before the number propagates through every IRS system. During that window, some electronic federal tax payments and e-filed returns may not go through. Most business owners find the number is fully recognized within a few weeks.

Store the CP 575 somewhere safe. Banks ask for it when you open a business account, and the IRS treats it as the official proof of assignment. If you lose it, request a 147C verification letter by calling 800-829-4933, keeping the 30-day availability window in mind for newly issued EINs.

When you open a New Mexico business bank account, expect the bank to ask for more than the EIN itself. Bring a government-issued photo ID, your Articles of Organization (LLC) or Articles of Incorporation (corporation), any operating or partnership agreement, and your DBA certificate if you use a trade name.

Register With New Mexico for a State Tax ID

The federal EIN covers you at the federal level. New Mexico requires a separate Business Tax Identification Number (BTIN) from the Taxation and Revenue Department, and you need the federal EIN in hand before you can apply for it.²

The BTIN is also free. Apply online through the New Mexico Taxpayer Access Point at tap.state.nm.us, or submit Form ACD-31015 at a district tax office.¹² Registration sets up your accounts for New Mexico’s gross receipts tax and any other applicable taxes. Any business engaging in business in New Mexico must complete this step, so do not assume the federal EIN alone makes you compliant.

When a New EIN Is Required Later

Changing your business name or address does not require a new EIN. Changing ownership or structure usually does, and the rules vary by entity type.¹³

Sole proprietors need a new EIN when they incorporate, form a partnership, or declare bankruptcy.
Corporations need a new EIN when they receive a new charter from the secretary of state, become a subsidiary, convert to a partnership or sole proprietorship, or merge into a new corporation.
Partnerships need a new EIN when they incorporate, dissolve and reform, or when one partner takes over as a sole proprietor.
LLCs need a new EIN when they terminate and form a new corporation or partnership. Converting a partnership LLC’s tax classification to an S corporation or regular corporation does not require a new EIN.¹³

Keep Your EIN Information Current

If the business moves or you change the responsible party on file, submit Form 8822-B to the IRS. Changes to the responsible party must be reported within 60 days.¹⁴ The task takes five minutes and keeps IRS notices from ending up with the wrong person at the wrong address.

1
Internal Revenue Service. Get an Employer Identification Number
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New Mexico Business Portal. Obtain Tax ID Numbers and Register a Business
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Internal Revenue Service. Single Member Limited Liability Companies
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Federal Trade Commission. FTC Warns Operators of Websites that Charge for an Employer Identification Number and Claim Affiliation with the IRS
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Internal Revenue Service. Responsible Parties and Nominees
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Internal Revenue Service. U.S. Taxpayer Identification Number Requirement
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Internal Revenue Service. Instructions for Form SS-4
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Internal Revenue Service. Form SS-4 Application for Employer Identification Number
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National Taxpayer Advocate. When Taxpayers Struggle to Obtain an EIN, Everyone Loses
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Internal Revenue Service. Employer Identification Number
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Internal Revenue Service. Instructions for Form SS-4
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New Mexico Taxation and Revenue Department. Who Must Register a Business
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Internal Revenue Service. When to Get a New EIN
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Internal Revenue Service. About Form 8822-B, Change of Address or Responsible Party – Business