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A tax identification number (TIN) is a nine-digit number that the Internal Revenue Service (IRS) uses to identify individuals and businesses for federal tax purposes.
TIN is an umbrella term that includes several types of numbers, including Social Security numbers, employer identification numbers (EINs), and individual taxpayer identification numbers (ITINs). The IRS and Social Security Administration issue TINs to different types of taxpayers.
Individuals have to include their TIN on tax documents, and business owners use their TINs to pay taxes, process payments, hire employees, and stay compliant with federal and state tax obligations.
This guide covers the types of TINs, which one your business needs, and how to apply for it.
What is a tax identification number (TIN)?
A TIN is any number the IRS uses to identify a taxpayer on official documents. It appears on tax returns, informational forms like 1099s and W-2s, and any application that requires federal tax identification. The nine-digit format stays consistent across TIN types, but eligibility varies based on type, as does the issuing entity.
The TIN you’ll need depends on whether you’re a US citizen, a resident alien, a non-resident earning US income, a business with employees, a parent in the process of adoption, or a tax professional preparing returns for clients.
TIN vs. tax ID number: Is there a difference?
Tax ID number and TIN mean the same thing. Both refer to the number that the IRS uses to track federal tax accounts. The terms appear interchangeably in IRS documents, bank applications, and payment platform verification forms.
Types of tax identification numbers
There are five types of TINs:
- Social Security number (SSN)
- Employer identification number (EIN)
- Individual taxpayer identification number (ITIN)
- Preparer tax identification number (PTIN)
- Adoption taxpayer identification number (ATIN)
Social Security number (SSN)
The Social Security Administration (SSA) issues SSNs to US citizens and eligible residents. It’s the most widely recognized TIN: Individuals use it to file personal income taxes, and sole proprietors can use it as their primary business tax ID. SSNs follow the format XXX-XX-XXXX and appear on Social Security cards.
Employer identification number (EIN)
The IRS issues EINs to businesses and organizations for federal tax purposes. EINs follow the format XX-XXXXXXX and are also known as a federal employer identification number (FEIN), federal tax identification number, or federal taxpayer identification number.
Businesses use EINs to file business tax returns, open business bank accounts, hire employees, and process payroll. An EIN stays with your business permanently; it doesn’t change when ownership or structure changes.
Individual taxpayer identification number (ITIN)
The IRS issues ITINs to individuals who need to file US federal taxes but aren’t eligible for an SSN. These individuals include non-resident aliens, foreign nationals, and spouses or dependents of US citizens or resident aliens. An ITIN begins with the digit 9 and follows the format 9XX-XX-XXXX. ITINs don’t authorize work in the US or qualify holders for Social Security benefits.
If you don’t use your ITIN on a federal tax return for three consecutive years, it will expire on December 31 of the third year you don’t use it. Renewal requires a new Form W-7 marked as a renewal application.
Preparer tax identification number (PTIN)
The IRS requires a PTIN for “anyone who prepares or assists in preparing federal tax returns for compensation.” Tax preparers register online through the IRS Tax Professional PTIN System for an $18.75 annual fee. If you hire a tax preparer, you can ask for their PTIN to confirm that they have registered with the IRS.
Adoption taxpayer identification number (ATIN)
The IRS issues ATINs as temporary identifiers to adoptive parents who can’t yet obtain an SSN for the child. You can apply for an ATIN for domestic adoptions, or foreign adoptions where the child/children are resident aliens or have a certificate of citizenship.
An ATIN lets adoptive parents claim the child as a dependent on their tax return, which means you won’t need one if you’ll be able to get an SSN for the child by the time you file your taxes. Parents apply using Form W-7A.
Here’s a side-by-side look at all five TIN types:
| TIN type | Who uses it | Issued by | How to apply | Cost | Time to receive |
|---|---|---|---|---|---|
| SSN | US citizens, eligible residents | Social Security Administration | Form SS-5 at an SSA office | Free | 2–4 weeks |
| EIN | Businesses, organizations, employers | IRS | Online at IRS.gov (or submit Form SS-4 by mail, fax, or phone) | Free | Instant (online and phone); four days (fax); four weeks (mail) |
| ITIN | Non-US residents ineligible for SSN | IRS | Form W-7 by mail, at IRS TAC, or via a VITA site | Free or fee-based, depending on application method | 7–11 weeks |
| PTIN | Paid tax preparers | IRS | Online via IRS Tax Professional PTIN System | $18.75 | About 15 minutes |
| ATIN | Adoptive parents (pending domestic adoption) | IRS | Form W-7 A by mail | Free | 4–8 weeks |
Why a TIN matters for your business
Here are some common scenarios where your business TIN will come into play, whether it’s an EIN or your own SSN/ITIN.
Tax filing and compliance
The IRS requires a TIN on every federal tax return, W-9 form, and 1099 filing. Without one, the IRS can’t process a return or match the right taxpayer account to reported income.
If your business pays independent contractors more than $2,000 in a calendar year, as of 2026, you need to collect each contractor’s TIN via Form W-9 and file a 1099-NEC.
If a contractor fails to provide a TIN, you, as the paying business, must withhold 24% of payments as backup withholding under IRS rules.
Opening a business bank account and accessing credit
Banks and credit institutions require an EIN to open a business bank account, apply for a business loan, or establish business credit. This doesn’t apply to sole proprietors, who can use their SSN as their TIN.
Hiring employees and paying contractors
As a business, you’ll use your EIN to set up payroll, file quarterly employment tax returns (Form 941), and issue W-2s at the end of each year. For independent contractors, collecting a TIN via Form W-9 is a prerequisite to paying them and filing any required 1099-NEC forms. Missing or incorrect TINs on filed forms can result in IRS penalties for the business.
Which tax ID number does your business need?
The TIN your business needs will depend on your business structure.
Sole proprietors and single-member LLCs
Sole proprietors and single-member LLCs without employees can use their SSN as their business TIN. Many sole proprietors choose to get an EIN to keep their Social Security number off vendor forms, W-9s, and contractor agreements.
If you’re a sole proprietor without an EIN setting up Shopify Payments, you’ll use your SSN or ITIN when you verify your account.
If you have employees, plan to hire, or want to open a dedicated business bank account, you’ll need an EIN.
Corporations, partnerships, and multimember LLCs
Corporations, partnerships, or multimember LLCs need an EIN. An EIN identifies the business as a separate taxpaying entity, while an SSN identifies an individual. If you’ve ever hired an employee, have excise tax obligations, or offer retirement plans, the IRS requires an EIN.
Non-US residents earning income in the US
If you’re not a US resident, earn income in the US, and aren’t eligible for an SSN, you’ll need an ITIN to file a federal tax return. This number exists only for federal tax filing. Consult a tax professional to determine your specific obligations based on your country of residence and business structure.
How to get a tax ID number
The IRS makes it easy to apply for a TIN, with online, in-person, and mail-in options.
How to apply for an EIN (free, online with the IRS)
The IRS EIN online application is free and available at IRS.gov. To qualify, your principal place of business must be in the US or a US territory, and the responsible party must have a valid TIN (an SSN, ITIN, or existing EIN). The IRS issues your EIN immediately upon completing the online application.
To apply for an EIN online:
- Go to the IRS EIN online application at IRS.gov.
- Select your business entity type.
- Enter the responsible party’s personal information and TIN.
- Complete the application and download your EIN confirmation letter (CP 575).
You can access the online application from 6 a.m. to 1 a.m. ET from Monday through Friday, 6 a.m. to 9 p.m. ET on Saturdays, and 6 p.m. to 12 a.m. ET on Sundays.
If you can’t apply online, you can submit Form SS-4 by mail, fax, or phone. Fax processing takes about four days; mail processing takes about four weeks. Phone processing is immediate, but is only open to international EIN applicants.
How to apply for an ITIN
Non-US residents and others ineligible for an SSN apply for an ITIN using Form W-7, available at IRS.gov. The application requires proof of identity (a valid passport covers both requirements) and proof of foreign status. Most applicants must include a completed federal tax return with their W-7 unless they meet a specific exception listed in the Form W-7 instructions.
Applications go to the IRS by mail, in person at an IRS Taxpayer Assistance Center, or through an IRS-authorized Certifying Acceptance Agent. Mail processing takes seven to 11 weeks. If your ITIN expires, you can renew it using the same Form W-7.
Where to find your tax ID number
If you’re not sure what your SSN or EIN is, here are the documents where you can find it.
Finding your SSN
Your SSN appears on several documents. Check these if you need to locate it:
- Your Social Security card (issued by the SSA)
- Previously filed federal tax returns
- W-2 forms from past employers
- Correspondence from the SSA
Unlike an EIN, an SSN is tied directly to your personal identity and credit history.
Finding your EIN
If you’ve already received an EIN and need to locate it, check these sources:
- The IRS CP 575 confirmation letter that was issued when you applied
- Previously filed federal business tax returns
- Bank and financial account paperwork opened under the business name
- IRS Letter 147C (a verification letter you can request by calling the IRS Business and Specialty Tax Line)
Tax ID numbers for ecommerce and online sellers
Shopify store owners can use different types of TINs to register for Shopify Payments and use Shopify Tax.
TIN requirements for Shopify Payments account verification
Shopify Payments uses your TIN to verify your business identity as part of payment processing compliance requirements. The TIN you need depends on the business type you select during Shopify Payments setup:
- Single-person businesses without an EIN can enter their SSN or ITIN
- All other business types (multi-member LLCs, corporations, partnerships) require an EIN
The information you submit must match IRS records exactly. Name misspellings, entity type mismatches, or TIN errors can delay or block account verification. If you’re not sure which TIN applies to your business structure, consult a tax professional before completing the Shopify Payments verification step.
How your EIN connects to Shopify Tax automated filing
Shopify Tax automates sales tax calculation and filing across US states. When you set up automated filing, Shopify Tax uses your EIN, FEIN, or SSN to access your state Department of Revenue (DOR) account and file sales tax for you.
As with Shopify payments, the business details you provide, including your EIN or SSN, must match exactly what’s registered with each state’s DOR, or you risk a failed filing.
Sales tax IDs are separate from your federal TIN. A sales tax ID (also called a sales tax permit or reseller certificate) is a state-level number that identifies your business to a state’s revenue authority—not to the IRS.
You register a sales tax ID with each state where you have a tax obligation, then configure those IDs in Shopify’s Taxes and Duties settings alongside your collection and filing preferences.
Shopify Tax handles state sales tax filing only. Federal income tax filing—including annual business returns and quarterly estimated payments—is the store owner’s responsibility. A tax professional or accountant can help with federal filing obligations and ensure that you follow all federal tax laws.
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What is a tax identification number FAQ
Is my SSN my tax ID number?
Yes, for most individuals. A Social Security number is a type of TIN, and the IRS recognizes it as your federal tax identifier for personal returns. Sole proprietors can also use their SSN as their business TIN if they don’t have an EIN. If you’re an employee or an individual taxpayer, your SSN is the TIN you’ll use on federal forms and returns.
Is the employer identification number the same as the tax ID?
An EIN is a type of tax ID number issued by the IRS to businesses and organizations. When a bank or vendor asks for a tax ID, they’re usually asking for an EIN if you’re representing a business. But a sole proprietor without an EIN can provide their SSN instead. Both are valid TINs; the right one depends on your business structure.
Is the tax identification number the same as EIN?
Not always. TIN is the umbrella term for all federal tax identifiers: EINs, SSNs, ITINs, PTINs, and ATINs are all TINs. An EIN is the specific TIN issued to businesses by the IRS. In a business context, when someone asks for your TIN, they need your EIN. For individuals filing personal federal income tax returns, the TIN is usually an SSN or ITIN.
How can you check a TIN online?
You can’t look up individual TINs publicly. The IRS offers a TIN Matching program for authorized payers. Businesses that file 1099 forms can use them to verify a contractor’s TIN against IRS records before filing. Access to the TIN Matching program requires registration at IRS.gov. To verify your own EIN, request IRS Letter 147C by calling the Business and Specialty Tax Line.
What happens if a TIN is missing?
If a contractor doesn’t provide their TIN to a business, the business that’s paying the contractor must withhold 24% of payments as backup withholding under IRS rules.
Businesses that pay contractors who fail to collect TINs or file required 1099 forms can face penalties ranging from $60 to $680 per return, depending on the lateness or whether the IRS believes there was “intentional disregard.” Without a TIN, you also can’t file a federal return or complete required federal forms.
