What’s a tax identification number, and how can you get one?

Ever filled out a tax form and wondered what that string of numbers really means? That’s your tax identification number, or TIN—the code the government uses to link your income, payments, and returns to you. Whether you’re starting a new job or launching a business, you’ll need the right TIN to keep things running smoothly. 

What’s a TIN?

A TIN is a unique number the Internal Revenue Service (IRS) uses to track how you pay taxes. Everyone who files a return or reports income needs one, whether you’re an employee, contractor, or business owner. In the U.S., a Social Security number (SSN) is the most common type of TIN. Still, there are others—like the employer identification number (EIN) for businesses and the individual taxpayer identification number (ITIN) for people who aren’t eligible for an SSN. 

No matter which type you use, your TIN connects your income, deductions, and tax payments to your record, making it essential for filing accurately and staying compliant with federal tax laws.

Types of TINs

The IRS and state agencies issue different TINs depending on who you are and why you’re applying. For example, you might be earning wages, running a company, or even filing without a Social Security number (SSN). Here’s a breakdown of the most common types and how each one works.

SSN

An SSN is the most common tax identification number and the one most people already have. It’s issued to U.S. citizens and eligible residents to track income, benefits, and tax responsibilities. If you earn wages or file a personal tax return, your SSN is the number you’ll use. Eligible parties can apply for this TIN by completing Form SS-5.

Employer Identification Number (EIN)

An EIN acts like a Social Security number, helping the IRS identify business entities. Companies, LLCs, and even sole proprietors rely on an EIN to handle responsibilities like hiring employees and filing tax returns. Applying is simple—businesses can request an EIN directly from the IRS.

Individual Taxpayer Identification Number (ITIN)

An ITIN is for people who aren’t eligible for an SSN but still need to pay taxes. The IRS commonly issues this number to nonresident aliens, their spouses, and dependents who must file a federal return. Having an ITIN allows them to stay compliant and access certain tax benefits. To apply, fill out Form W-7 and submit it with your tax return.

Taxpayer Identification Number for Pending U.S. Adoptions (ATIN)

An ATIN is a temporary number given to adoptive parents when a child’s Social Security number isn’t available yet. It allows parents to claim the child as a dependent and receive tax benefits while the adoption is still pending. Once everything is finalized and the child receives an SSN, the ATIN is no longer needed.

Preparer Taxpayer Identification Number (PTIN)

A PTIN is required for anyone who gets paid to prepare federal tax returns. It identifies the tax professional on the returns they file and ensures the IRS can track who prepared the paperwork. By doing so, the PTIN helps keep the filing process accountable and transparent. 

State taxpayer identification number

Some states issue their own taxpayer IDs in addition to federal numbers. These state-issued IDs are often needed to file state returns, pay state taxes, and register a business locally. Having both federal and state numbers ensures taxpayers meet all levels of compliance.

How do you get a TIN?

Getting a tax identification number isn’t complicated, but the process does depend on whether you’re applying as an individual or on behalf of a business. Here’s how each works.

1. Register your business with the state

Before applying for a federal tax ID, you must register your business with the state where you plan to operate. This process typically involves choosing a business structure, such as a corporation, partnership, or LLC, and registering your business name with the state's Secretary of State office or business registry agency.

2. Gather required information and documents

To complete the tax ID application, you'll need specific details about your business, including the formation date, legal business name and address, the owner's SSN or ITIN, and the number of employees you expect to hire in the next 12 months.

3. Submit your application

Once you've registered your business, gathered the necessary information, and chosen an application method, you'll need to provide the details to the IRS by filling out Form SS-4. Be sure to complete all required fields accurately and submit the form using your selected method. If applying online, you'll receive your business tax ID instantly.

What is a foreign tax ID? 

A foreign tax identification number is the equivalent of a TIN outside of the U.S. Each country issues its own version to track income and tax responsibilities for residents, businesses, and sometimes foreign investors. If you’re filing U.S. tax forms and you live abroad, or you’re claiming tax treaty benefits, the IRS may ask you to provide your foreign TIN.

Are you unable to provide a foreign TIN?

If you don’t have a foreign TIN, the IRS may require an explanation on certain forms, such as the W-8BEN and Form 8938 (Statement of Specified Foreign Financial Assets). In many cases, you’ll need to state why you can’t provide one—whether your country doesn’t issue them, you’re not required to have one, or your application is still pending. A couple of explanations you can use include:

• “I am not legally required to obtain a foreign TIN.”
• “My country of permanent residence does not issue foreign TINs.”

Understanding TINs and simplifying global payroll with Oyster

Understanding TINs is essential whether you’re an individual filing your first return, a business applying for an EIN, or a federal employer working with international talent. From SSNs to foreign TINs, each number plays a role in keeping tax reporting accurate and compliant.

If you’re hiring or expanding across borders, though, the complexity multiplies. That’s where Oyster can help. Oyster makes global hiring, running payroll, and filing taxes simple, so you can focus on growing your team without worrying about regulatory roadblocks. Learn more about how Oyster works and see how we can support your business every step of the way.

Disclaimer: This article and all information in it is provided for general informational purposes only. It does not and is not intended to constitute legal or tax advice. You should consult with a qualified legal or tax professional for advice regarding any legal or tax matter and prior to acting (or refraining from acting) on the basis of any information provided on this website.