A Taxpayer Identification Number (TIN) is a unique number used by the US Internal Revenue Service (IRS) to track individuals, businesses, and other entities for tax purposes.

The IRS uses a TIN to process tax returns, match reported income, issue refunds, enforce withholding requirements, and monitor compliance with federal tax laws.

Below, we’ll explain the different types of TINs that are available—including social security numbers (SSNs), Employer Identification Numbers (EINs), Individual Taxpayer Identification Numbers (ITINs), and Preparer Tax Identification Numbers (PTINs)—and why they matter for individuals and businesses.

What’s in this article?

• What are the different types of TINs?
  
• How and where to apply for TINs
  
• Why is a TIN important?
  
• How TINs are used by the IRS and other agencies
  
• How to determine which type of TIN you need
  
• TIN vs. EIN vs. SSN: What’s the difference?
  
• How Stripe Tax can help
  
• FAQs about taxpayer ID numbers
  

What are the different types of TINs?

The IRS recognizes several types of TINs. Each TIN serves a specific tax reporting purpose. Below, we’ll cover each type of TIN and why they are used.

Social Security number (SSN)

The Social Security Administration (SSA) issues a nine-digit Social Security Number to US citizens and eligible residents. Individuals use an SSN to file federal income taxes and report wages. Sole proprietors and single-member LLCs can also use an SSN to file business taxes, although businesses must collect the nine-digit SSNs of employees and independent contractors for annual reporting (such as Form 1099-NEC).

EIN

The Internal Revenue Service (IRS) assigns a nine-digit Employer Identification Number (EIN) to businesses for payroll taxes, corporate filings, and business tax reporting. Corporations, partnerships, multimember LLCs, and nonprofits use an EIN to manage payroll, open business bank accounts, and apply for business licenses. Eligible entities can apply for an EIN for free online, by fax, mail, or phone.

Individual Taxpayer Identification Number (ITIN)

The IRS issues an Individual Taxpayer Identification Number (ITIN) to foreign nationals, nonresidents, and dependents who are required to file US taxes but are ineligible for an SSN. These nine-digit identifiers always begin with the number “9.” Businesses frequently encounter ITINs when processing tax reporting for foreign investors or international independent contractors. Applicants must submit Form W-7 to the IRS, and processing typically takes up to seven weeks.

Preparer Tax Identification Number (PTIN)

The IRS issues a Preparer Tax Identification Number (PTIN) to paid tax professionals who prepare and file federal tax returns on behalf of clients. Tax professionals include certified public accountants (CPAs), enrolled agents, and tax advisers. Unlike other tax identifiers, a PTIN must be renewed annually before each tax season so the IRS can accurately track tax return preparation. Professionals can apply for or renew a PTIN online or by mail.

Adoption Taxpayer Identification Number (ATIN)

The IRS issues a temporary, nine-digit Adoption Taxpayer Identification Number (ATIN) to prospective adoptive parents who are in the process of legally adopting a child. Taxpayers use an ATIN to identify the child on their federal income tax returns so they can claim dependency exemptions or child care credits while the domestic adoption is pending. These numbers are unique because they automatically expire after two years, at which point the final adoption allows the parents to secure a permanent SSN for the child.

How and where to apply for TINs

The application process and processing times vary significantly depending on the specific taxpayer identifier you need to secure. Below is a quick breakdown of how and where to apply for each tax identification number:

How to apply for an SSN

To apply for a Social Security Number, you must complete Form SS-5 and submit it along with original documents proving your identity, age, and citizenship or lawful immigration status to a local Social Security Administration (SSA) office. Applications are generally submitted at birth via the hospital, or in person at an SSA branch if an adult is applying.

How to apply for an EIN

The fastest way to get an Employer Identification Number is to apply online through the official IRS website, where the number is generated immediately upon completion of the digital form. Alternatively, businesses can apply by downloading Form SS-4 and submitting it via fax or mail to the designated IRS processing center.

How to apply for an ITIN

To secure an Individual Taxpayer Identification Number, you must fill out Form W-7 and mail it to the IRS along with your completed federal income tax return and original proof of identity or foreign status documents. You can also apply in person by scheduling an appointment at an IRS Taxpayer Assistance Center or visiting an IRS-authorized Certifying Acceptance Agent (CAA).

How to apply for a PTIN

Tax professionals can apply for or renew a Preparer Tax Identification Number online by creating an account on the IRS Tax Professional PTIN System, which takes about 15 minutes to complete. If you prefer to apply by paper, you can mail Form W-12 to the IRS, although processing takes four to six weeks.

How to apply for an ATIN

To request an Adoption Taxpayer Identification Number, prospective parents must complete Form W-7A and mail it to the IRS. The application must include legal documentation from an authorized placement agency or court proving that a domestic adoption is actively underway.

Why is a TIN important?

Businesses rely on TIN numbers to comply with federal tax laws and facilitate financial transactions. Here are the reasons why it’s important for businesses to have a TIN:

• Tax compliance: The IRS uses your TIN to track your tax payments and obligations. Filing without the proper TIN, or with an incorrect TIN, can lead to fines, backup withholding on payments, and slower tax processing.

• Legal compliance: The IRS requires a TIN for activities ranging from filing taxes and paying employees to withholding taxes. You can’t legally conduct business, hire employees, or withhold taxes without the appropriate TIN.

• Banking and financial transactions: Financial institutions use your TIN to verify your business’s identity when you open a bank account, apply for loans, or seek other financial services. A valid TIN is required to access financial tools ranging from lines of credit to payroll accounts.

• Employee and contractor payments: When you’re running payroll, you need to ensure you have accurate TINs for each employee and independent contractor. Without the correct TINs, you can’t issue W-2s or 1099s, which can cause tax withholding and reporting issues.

• Credibility: A registered EIN or TIN signals to banks that your business is established and follows federal tax laws. Certain transactions can also require one, such as creating vendor accounts and applying for commercial insurance.

• Audit preparedness: Proper TIN documentation is required to complete an audit. TINs link your income, payments, and withholdings with your business.

How TINs are used by the IRS and other agencies

TINs serve as unique identifiers for individuals and businesses in a wide range of contexts. Below are some of the ways the IRS and other agencies use TINs.

IRS

• Tax filings: The IRS uses TINs to track all tax-related activity and verify that individuals and businesses are accurately reporting their income. The IRS uses these numbers to match reported earnings with submitted tax forms for consistency across filings. The IRS also uses TINs to properly credit taxpayers’ payments and refunds.

• Withholding and payments: Businesses use employee TINs (usually SSNs) to properly withhold income tax from payroll. Similarly, payments made to independent contractors require either an SSN, an EIN, or an ITIN. These are used to ensure proper tax withholding.

• Tax credits and deductions: The IRS uses TINs to verify eligibility when businesses or individuals claim credits or deductions. For example, businesses that claim the Work Opportunity Tax Credit must provide TINs for qualifying employees.

SSA

The SSA uses SSNs to record employee wages and calculate Social Security retirement and disability benefits. Businesses file employee wages and benefits with the SSA through annual W-2 filings, which include the employee’s SSN. The SSA uses these records to calculate Social Security benefits when employees retire or file for disability.

State tax agencies

State revenue departments use TINs for income tax collection and enforcement at the state level. They use TINs to verify that taxpayers are accurately reporting and paying their obligations to the state.

Financial institutions

Banks, investment firms, and credit unions use TINs to report financial information to the IRS. For example, when interest or dividends are paid out on an account, the financial institution must issue a 1099 form that lists the recipient’s TIN. The IRS cross-checks the information to ensure that taxpayers are accurately reporting investment income on their returns.

Financial institutions are also required to gather TINs as part of the Know Your Customer (KYC) process to confirm account holders’ identities. This helps mitigate the risk of money laundering and tax evasion.

Department of Labor

The Department of Labor uses TINs to track employees’ earnings for unemployment insurance. Employers must report wages and tax withholdings using TINs so that workers are eligible for unemployment benefits if they lose their jobs.

Department of Health & Human Services (HHS)

The HHS uses TINs (in the form of SSNs) to track eligibility for Medicare, Medicaid, and other federal programs that provide benefits based on income or employment status. It uses TINs to grant individuals the benefits to which they’re entitled and to combat fraud and improper payments.

Foreign governments and international tax agencies

In some cases, the IRS may share TINs with foreign governments for tax treaty purposes or to comply with international tax regulations. For example, the Foreign Account Tax Compliance Act (FATCA) requires foreign financial institutions to report TINs for US account holders to help fight tax evasion involving offshore accounts.

Audits and enforcement

The IRS and other regulatory agencies use TINs for auditing purposes and to track financial transactions, validate tax filings, and confirm income is being reported accurately. Agencies use TINs to trace income and payments across sources and check for fraud or noncompliance.

Treasury and federal payments

If you do business with the US government, agencies might request a TIN for payment processing and compliance.

How to determine which type of TIN you need

Choosing the right TIN depends on your specific circumstances. Here’s how to determine which TIN you’ll need.

SSN

US citizens, permanent residents, and authorized temporary workers use an SSN to file personal income taxes, report wages, and access government benefits. Sole proprietors and single-member LLCs without employees can also use their SSN to report business income on a Schedule C (Form 1040) alongside their personal tax return.

• If you are an individual filing personal taxes or running a single-owner business without employees, use an SSN.
  

EIN

The IRS requires an EIN for all corporations, partnerships, and multimember LLCs. Any business entity must have an EIN if it hires employees, files excise or employment tax returns, operates a business bank account, or applies for commercial financing.

• If you operate a multiowner business, have employees, or need a business bank account, use an EIN.
  

ITIN

The ITIN serves non-US citizens, nonresidents, and foreign investors who have US tax filing obligations but are legally ineligible for an SSN. It is commonly used to report domestic rental income, investment returns, or independent contractor earnings, as well as to claim foreign dependents.

• If you must file US taxes but do not qualify for an SSN, use an ITIN.
  

PTIN

The IRS mandates a PTIN for all tax professionals who prepare or assist with federal tax returns for financial compensation. This includes CPAs, enrolled agents, and commercial tax advisers. This credential does not replace personal tax IDs and requires manual renewal prior to every tax season.

• If you prepare or sign federal tax returns for compensation, use a PTIN.
  

Adoption Taxpayer Identification Number (ATIN)

The IRS grants a temporary ATIN to prospective parents who are in the process of legally adopting a US citizen or resident child. It allows taxpayers to claim the child as a dependent on their federal returns while the final domestic adoption and permanent SSN are pending.

• If you are claiming a child on your tax return before their final adoption is complete, use an ATIN.
  

If you’re unsure which TIN applies to you, consider your business’s structure and obligations, your residency status, and whether you have employees. Consult a tax professional to confirm you’re using the correct TIN for your specific situation to avoid compliance issues and potential penalties in the future.

TIN vs. EIN vs. SSN: What’s the difference?

How Stripe Tax can help

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• Digital goods and services in all US states and over 100 countries
  
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Stripe Tax can help you:

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FAQs about taxpayer ID numbers