A Federal ID Number and a TIN are related but not identical. “Federal ID Number” is informal shorthand that almost always means an Employer Identification Number (EIN), while a Taxpayer Identification Number (TIN) is the IRS’s umbrella label for every nine-digit identifier used in the federal tax system. Every EIN is a TIN, but not every TIN is what people are pointing to when they say “Federal ID Number.” Understanding the difference between a federal ID number vs TIN comes down to knowing which specific number the phrase is standing in for.
What People Mean by “Federal ID Number”
When a bank, vendor, or form asks for your “Federal ID Number,” they’re almost always asking for an EIN. You may also see it written as Federal Employer Identification Number (FEIN) or Federal Tax Identification Number (FTIN). All three phrases point to the same nine-digit number the IRS assigns to business entities. It functions like a Social Security Number for a company.
Corporations, partnerships, multi-member LLCs, non-profits, trusts, and estates all need an EIN. Sole proprietors can often use their personal SSN instead, but they must get an EIN once they hire employees or change their structure to a corporation or partnership. Beyond tax filings, the EIN is required for practical business tasks like opening a business bank account, applying for credit, and running payroll.
The EIN’s core purpose is to separate a business entity’s tax obligations from the owner’s personal finances. A corporation files its income tax return on Form 1120 using its EIN; a partnership files Form 1065. That separation matters for both tax reporting and legal liability.
What a TIN Actually Is
A Taxpayer Identification Number is the nine-digit number the IRS uses to identify anyone in the federal tax system. The IRS matches income reported on forms like the W-2 and 1099 against what the taxpayer reports on their annual return using this number. Without a valid TIN, you can’t file a federal tax return, and any income paid to you may be subject to 24% backup withholding until you provide one.
The IRS recognizes five types of TINs, and the EIN is only one of them:
- Social Security Number (SSN), issued by the Social Security Administration to U.S. citizens and eligible residents.
- Employer Identification Number (EIN), issued by the IRS to businesses, trusts, estates, and other entities.
- Individual Taxpayer Identification Number (ITIN), issued by the IRS to individuals who need to file but can’t get an SSN.
- Adoption Taxpayer Identification Number (ATIN), a temporary IRS-issued number for a child in a pending adoption.
- Preparer Tax Identification Number (PTIN), issued to paid tax return preparers.
Each serves a different population, but they all work the same way at the system level: they let the IRS track who owes what. So “TIN” is a category, and “EIN” is a member of that category. When someone says “Federal ID Number,” they’ve almost always narrowed it to the EIN without saying so.
How the Other TINs Differ From an EIN
The SSN is the most common TIN and is used for personal income tax returns, wage reporting, and Social Security benefit calculations. Certain credits, like the Child Tax Credit, specifically require the child to have an SSN. A child with only an ITIN doesn’t qualify.
The ITIN exists for people who need to file a federal return but aren’t eligible for an SSN, including nonresident aliens, resident aliens, and their spouses and dependents. It’s formatted like an SSN but always begins with the digit 9. It exists solely for federal tax purposes and doesn’t authorize work or change immigration status. An ITIN also expires if you don’t use it on a federal return for three consecutive years, and you’ll need to renew it on Form W-7 before using it again.
The ATIN is a temporary number for a child in a domestic or foreign adoption when the adopting parents can’t yet obtain an SSN for the child. It lets them claim the child as a dependent while the adoption is being finalized. The IRS automatically deactivates the ATIN within two years of issuance, and once the child receives an SSN, all future filings must use that number.
The PTIN identifies the preparer rather than the taxpayer. Anyone who prepares federal tax returns for pay must register for one and include it on every return they prepare.
Where the Distinction Actually Matters
For most business owners, the practical answer to “Federal ID Number or TIN?” is that you’re being asked for your EIN. But the terms aren’t interchangeable in every situation, and a few overlaps trip people up.
A sole proprietor with no employees can use their SSN as the business’s TIN on federal filings. In that case, the “TIN” the IRS is looking for is an SSN, not an EIN, and the business technically has no separate Federal ID Number at all. Once that sole proprietor hires employees or incorporates, an EIN becomes required.
A state tax identification number and your federal EIN are also two different numbers, issued by two different agencies. The EIN comes from the IRS and covers federal taxes. A state tax ID comes from your state’s revenue or taxation department and covers state-level obligations like income tax withholding and sales tax. If your business operates in a state that taxes income, you’ll need both. Handing over your state ID when a form asks for your Federal ID Number is a common mistake.
How to Get an EIN
If you’ve worked out that the number you actually need is an EIN, the IRS issues them at no charge through Form SS-4. The fastest route is the online application at IRS.gov, which generates your EIN immediately. The online tool is available Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern, Saturdays from 6:00 a.m. to 9:00 p.m., and Sundays from 6:00 p.m. to midnight. You’re limited to one EIN application per responsible party per day.
To use the online application, you need to be located in the United States or a U.S. territory, and the person applying must have a valid SSN, ITIN, or EIN of their own. The applicant must be the “responsible party,” meaning the individual who controls the entity or manages its funds. You’ll provide the entity’s legal name, address, and type.
If you can’t use the online tool, you can fax the completed Form SS-4 and expect your EIN within about four business days. Mailing the form is the slowest option at roughly four to five weeks.
One warning: the application is free directly from the IRS. Third-party websites sometimes charge fees to file what is essentially the same free application on your behalf. If a site is asking for payment, go to IRS.gov and apply directly.
When a Business Needs a New EIN
Changing your business name or address does not require a new EIN. Changing the entity’s ownership or structure generally does. The specific triggers depend on what type of entity you have:
- Sole proprietors need a new EIN if they incorporate, form a partnership, or declare bankruptcy.
- Corporations need a new EIN if they convert to a partnership or sole proprietorship, or if two corporations merge and create a new entity.
- Partnerships need a new EIN if they incorporate, dissolve so one partner continues as a sole proprietor, or end the partnership and start a new one.
- LLCs need a new EIN if they terminate and form a new corporation or partnership.
Filing under the wrong number can trigger IRS notices and processing delays. The IRS maintains a guide on its website specifically covering when a new EIN is and isn’t required.