When a tax form asks for your “tax ID type,” it’s asking which category of Taxpayer Identification Number you use with the IRS. For most people that’s a Social Security Number. People who owe U.S. tax but can’t get an SSN use an Individual Taxpayer Identification Number instead. Businesses, and estates that keep earning income after someone dies, use an Employer Identification Number. A handful of narrower types exist for specific situations, but nearly every form comes down to those three.
Why the Form Asks
Federal law requires every person or entity filing a tax return to include an identifying number so the IRS can match income, payments, and returns to the right taxpayer.1Office of the Law Revision Counsel. 26 USC 6109 – Identifying Numbers The “type” tells the payer or agency whether they’re dealing with an individual, a business, an estate, or something else, which in turn determines how your income gets reported and taxed.
The stakes for getting it wrong are concrete. If you don’t give a correct TIN to a payer who requests one, the payer is generally required to withhold 24 percent of your payments and send that money to the IRS as backup withholding.2Internal Revenue Service. Backup Withholding You get credit for the withheld amount when you file, but the cash is out of your hands until then. Checking the wrong entity box on a Form W-9 can also cause the payer to issue the wrong kind of 1099, which triggers IRS matching errors months later.
Social Security Number (SSN)
The SSN is the default. The Social Security Administration issues SSNs to U.S. citizens and to noncitizens authorized to work in the United States or who have another valid reason for one.3Social Security Administration. Request a Social Security Number for the First Time Federal tax law names the SSN as the identifying number for individuals, so unless you fall into a special category, your SSN is what goes on your return, your W-4, and every bank or brokerage form you fill out.1Office of the Law Revision Counsel. 26 USC 6109 – Identifying Numbers
If you have an SSN, that is your tax ID type as an individual. It appears in Box a of your W-2, at the top of Form 1040, and in the recipient field of any 1099 issued in your name. The format is XXX-XX-XXXX.
Individual Taxpayer Identification Number (ITIN)
If you have a U.S. tax filing obligation but don’t qualify for an SSN, you use an ITIN. It’s a nine-digit number the IRS issues after you submit Form W-7 along with your tax return and supporting identity documents.4Internal Revenue Service. About Form W-7, Application for IRS Individual Taxpayer Identification Number The most common applicants are nonresident aliens with U.S.-source income and resident aliens who haven’t received an SSN.
An ITIN is a tax-filing number and nothing more. It doesn’t grant work authorization and doesn’t entitle you to Social Security benefits.5Internal Revenue Service. Instructions for Form W-7 A valid passport proves both identity and foreign status in a single document; without one, you’ll need two documents, such as a foreign driver’s license or national ID plus a visa or civil birth certificate. Originals or certified copies only, and nothing expired.6Internal Revenue Service. ITIN Supporting Documents
ITINs expire. If yours isn’t used on a federal tax return for three consecutive tax years, it expires automatically on December 31 of that third year, and filing with an expired ITIN stalls processing and can hold up credits until you renew using Form W-7.7Internal Revenue Service. How to Renew an ITIN
Employer Identification Number (EIN)
An EIN is a Social Security Number for a business. Despite the name, you don’t need employees to need one. Partnerships, multi-member LLCs, corporations, and certain trusts all require an EIN to file federal returns and open business bank accounts.8Internal Revenue Service. Get an Employer Identification Number Keeping a separate EIN also keeps your personal SSN off business contracts and W-9s, which reduces your identity theft exposure.
EINs use a different format from SSNs and ITINs: XX-XXXXXXX rather than XXX-XX-XXXX. That formatting difference is often how a form’s software recognizes which type you’ve entered.
The Single-Member LLC Wrinkle
A single-member LLC without employees is a “disregarded entity” for income tax purposes, which means you report its income on your personal return using your own SSN. If that LLC hires an employee, it must get its own EIN for employment tax reporting.9Internal Revenue Service. Single Member Limited Liability Companies Many single-member LLC owners get an EIN anyway, because banks and vendors ask for one and it spares them from writing their SSN on every W-9.
When a Business Needs a New EIN
Changing your business name or opening a second location does not require a new EIN. Structural changes do. A sole proprietor needs a brand-new EIN when incorporating, forming a partnership, or declaring bankruptcy.10Internal Revenue Service. When to Get a New EIN If the change is only in the person responsible for the business, you keep the EIN but must notify the IRS on Form 8822-B within 60 days.11Internal Revenue Service. Form 8822-B Change of Address or Responsible Party – Business
TINs for Estates and Trusts
When someone dies, their SSN does not transfer to their estate. If the estate generates $600 or more in gross annual income, the personal representative must obtain a separate EIN and file Form 1041.12Internal Revenue Service. File an Estate Tax Income Tax Return Even a few months of interest, dividends, and rental income from the decedent’s assets can clear that threshold.
Trusts follow a similar pattern with control as the dividing line. A revocable living trust typically uses the grantor’s SSN while the grantor is alive because the IRS treats the assets as the grantor’s. Once the grantor dies and the trust becomes irrevocable, it needs its own EIN. If an irrevocable trust splits into separate shares for different beneficiaries, each share usually needs its own EIN as well.
Two Narrower Types Worth Knowing
Two additional TINs exist for specific situations. Most readers will never need them, but knowing what they are prevents confusion when the term comes up.
An Adoption Taxpayer Identification Number (ATIN) is a temporary number the IRS issues when you’re adopting a child domestically and can’t get the child’s SSN before your tax return is due. You apply on Form W-7A, and the ATIN expires automatically two years after issuance.13eCFR. 26 CFR 301.6109-3 – IRS Adoption Taxpayer Identification Numbers Once the adoption is finalized and the child has an SSN, you notify the IRS and the ATIN is deactivated.14Internal Revenue Service. Adoption Taxpayer Identification Number
A Preparer Tax Identification Number (PTIN) is required for anyone who prepares tax returns for compensation. The preparer includes it in the “Paid Preparer” section of every return they sign, which keeps their personal SSN off client returns.15Internal Revenue Service. Frequently Asked Questions – Do I Need a PTIN If you’re filing your own return, a PTIN is not something you need.
Picking the Right Box on a W-9
Form W-9 is where most freelancers and contractors first meet the tax ID type question. When a business hires you as a non-employee, they hand you a W-9 to collect your name, TIN, and entity type so they can report your payments to the IRS at year-end. The form has checkboxes for individuals, C corporations, S corporations, partnerships, trusts, and LLCs. Match the box to the number you’re supplying: an individual or sole proprietor giving an SSN checks “individual/sole proprietor”; an LLC taxed as a corporation checks the corporation box and gives the EIN.
The number you write also has to match the format the payer expects. SSNs and ITINs use XXX-XX-XXXX. EINs use XX-XXXXXXX.16Internal Revenue Service. Instructions for Forms 1099-MISC and 1099-NEC Keeping the same name and number on every document you sign is the simplest way to avoid IRS matching problems. A single transposed digit on a 1099 can generate a notice claiming you underreported income, and unwinding that takes months.