What Is a TIN Number for Taxes: Types, How to Apply, and Costs

A Taxpayer Identification Number (TIN) is the nine-digit number the IRS uses to identify you on any tax return, statement, or other document you file.¹ “TIN” is an umbrella term. It covers five different numbers, and the one you need depends on who you are and why you’re filing: a Social Security Number for most individuals, an Employer Identification Number for a business or other entity, an Individual Taxpayer Identification Number for people who owe U.S. tax but can’t get an SSN, an Adoption Taxpayer Identification Number for a child in a pending adoption, and a Preparer Tax Identification Number for anyone paid to prepare returns.

The Five Types of TIN and Who Uses Each

Federal law requires every person or entity filing a return to include an identifying number.¹ Which of the five you use is a matter of category, not choice.

Social Security Number (SSN)

The Social Security Administration issues SSNs to U.S. citizens and eligible noncitizens. Your SSN ties together employment, tax reporting, and federal benefits. Most people born in the U.S. receive one shortly after birth.² If you have an SSN, that is your TIN for personal tax purposes.

Employer Identification Number (EIN)

An EIN identifies a business, trust, estate, or other entity. Corporations, partnerships, and LLCs must have one. A sole proprietor needs one to hire employees or run certain retirement plans. Once assigned, an EIN is permanent: the IRS can deactivate it but never cancels it, and it cannot be transferred or reused.³⁴

Individual Taxpayer Identification Number (ITIN)

The IRS issues ITINs to people who have a federal tax obligation but aren’t eligible for an SSN. An ITIN is a tax processing number only. It doesn’t authorize work in the U.S., qualify you for Social Security benefits, or affect your immigration status. You also need one to claim tax treaty benefits that reduce withholding on U.S.-source income.⁵

Adoption Taxpayer Identification Number (ATIN)

An ATIN is a temporary number for a child in a domestic or foreign adoption when the child’s SSN isn’t yet available. It lets adoptive parents claim the child as a dependent while the adoption is pending. The ATIN deactivates automatically after two years if you haven’t provided the child’s SSN by then.⁶

Preparer Tax Identification Number (PTIN)

Anyone who prepares or helps prepare federal tax returns for pay must have a PTIN, and it must appear in the “Paid Preparer” section of every return they touch. Preparing returns for compensation without a current PTIN carries penalties under 26 U.S.C. § 6695.⁷⁸

How to Apply for the TIN You Need

Getting an SSN

If you weren’t assigned an SSN at birth, you apply through the Social Security Administration with documents proving your identity, citizenship or immigration status, and age.² Noncitizens generally must be authorized to work in the U.S. by the Department of Homeland Security to qualify.⁹ There is no fee.

Getting an EIN

You apply for an EIN on Form SS-4. The application asks for the entity’s legal name, the date the business started or was acquired, the reason you need the number, and the name and SSN or ITIN of a responsible party — a real person who owns, controls, or manages the entity’s funds and assets.¹⁰¹¹

The IRS online tool is the fastest route. It validates your entries in real time and issues the EIN immediately at no cost, but you must have a principal place of business in the U.S. or a U.S. territory and the responsible party’s SSN or ITIN. The IRS limits online applications to one per responsible party per day. Fax applications usually produce an EIN in about four business days. Mail applications take roughly four weeks.¹²¹³ The IRS never charges for an EIN. Third-party sites that offer to obtain one for a fee are charging for a free government service.

Getting an ITIN

You apply on Form W-7 and, in most cases, must attach the federal tax return that created the filing obligation.¹⁴ The form asks for your legal name, mailing address, date of birth, and any foreign tax identification numbers.

A valid passport is the only document that can stand alone, because it proves both identity and foreign status. Without a passport, you must submit at least two documents from the IRS’s approved list, together covering identity and foreign status. Acceptable options include a U.S. visa, a foreign driver’s license, a national ID card with photo and expiration date, a civil birth certificate, a USCIS photo ID, or a foreign military ID. Medical records are accepted only for dependents under six; school records only for student dependents under 24. Everything must be an original or a certified copy from the issuing agency. Notarized photocopies are not accepted.¹⁵

You have three ways to submit:

An IRS Taxpayer Assistance Center will review your Form W-7, authenticate most documents in person, and hand them back at the end of the appointment before mailing your application on. This is free, but appointments can take weeks.¹⁶
A Certified Acceptance Agent (CAA) authenticates your documents, helps complete Form W-7, submits the package, and returns your originals immediately. CAAs charge a fee, often between $150 and $300.¹⁷
You can mail Form W-7, your tax return, and original documents or certified copies directly to the IRS ITIN Operation. Certified mail gives you tracking and proof of delivery, which matters when your originals are in the envelope.

Processing generally takes about seven weeks, and nine to eleven weeks during the January 15 through April 30 tax season or for applications sent from overseas. The IRS mails a notice with your assigned ITIN once approved, and that notice is your official proof for future filings.⁵

Getting an ATIN

Adoptive parents apply by contacting the IRS during a pending adoption when the child’s SSN isn’t yet available. Once the adoption is finalized, get an SSN for the child and notify the IRS so it can deactivate the temporary number.⁶

Getting a PTIN

Paid preparers apply or renew through the IRS’s online PTIN system. The fee is $18.75 for 2026 and is non-refundable, and the PTIN must be renewed annually before the start of each filing season.¹⁸⁷

What It Costs

Almost every TIN is free when you apply directly to the issuing agency. SSN applications through the Social Security Administration carry no fee. EIN applications are free whether you file online, by fax, or by mail.¹² ITIN applications are free when submitted by mail, at an IRS Taxpayer Assistance Center, or through a Volunteer Income Tax Assistance (VITA) site.¹⁶

The PTIN is the exception at $18.75 for 2026.¹⁸ A Certified Acceptance Agent’s fee for helping with an ITIN is separate, typically $150 to $300. Websites that charge a fee for EIN applications are not the IRS.

When a TIN Can Expire or Change

ITINs Expire After Three Years of Non-Use

An ITIN that doesn’t appear on a U.S. federal tax return for three consecutive tax years expires on December 31 after that third year.¹⁹ For the 2026 filing season, ITINs not used for tax years 2022, 2023, and 2024 expired on December 31, 2025.²⁰ Filing with an expired ITIN can delay processing, block certain credits, and lead to penalties and interest.

To renew, submit a new Form W-7 with the same kinds of identity documents required for an original application, along with the return you’re filing, through the same three channels: mail, a Taxpayer Assistance Center, or a Certified Acceptance Agent.¹⁵ You don’t need to renew if the ITIN will only appear on information returns like Form 1099 and not on a return you file.¹⁹

EINs Are Permanent, but Details Change

An EIN never disappears. Even when a business closes, the IRS deactivates the number rather than cancelling it, and it stays tied to that entity forever. You cannot transfer an EIN to a new business, and changing entity type (converting a sole proprietorship to an LLC, for example) requires a new one.⁴

What does change is the information behind the EIN. Report changes to your business name, mailing address, physical location, or responsible party on Form 8822-B. A change in responsible party — a new principal officer of a corporation, a new trustee of a trust — must be reported within 60 days.²¹¹¹

1
Office of the Law Revision Counsel. 26 U.S.C. 6109 – Identifying Numbers
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Social Security Administration. Request a Social Security Number for the First Time
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Internal Revenue Service. Employer Identification Number
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Internal Revenue Service. If You No Longer Need Your EIN
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Internal Revenue Service. Individual Taxpayer Identification Number (ITIN)
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Internal Revenue Service. Adoption Taxpayer Identification Number
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Internal Revenue Service. PTIN Requirements for Tax Return Preparers
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Office of the Law Revision Counsel. 26 U.S.C. 6695 – Other Assessable Penalties With Respect to the Preparation of Tax Returns for Other Persons
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Social Security Administration. Social Security Numbers for Noncitizens
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Internal Revenue Service. Instructions for Form SS-4
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Internal Revenue Service. Responsible Parties and Nominees
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Internal Revenue Service. Get an Employer Identification Number
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Taxpayer Advocate Service. Getting an EIN
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Internal Revenue Service. About Form W-7, Application for IRS Individual Taxpayer Identification Number
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Internal Revenue Service. Instructions for Form W-7
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Internal Revenue Service. How to Apply for an ITIN
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Internal Revenue Service. ITIN Acceptance Agents
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Internal Revenue Service. IRS Reminds Tax Pros to Renew PTINs for the 2026 Tax Season
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Internal Revenue Service. How to Renew an ITIN
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Internal Revenue Service. Next Steps to Get Ready for 2026 Tax Filing Season
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Internal Revenue Service. Form 8822-B, Change of Address or Responsible Party – Business