What does “tax ID” actually mean?
Tax ID is an informal umbrella for any number a tax authority uses to identify a filer. It covers 4 things: the federal EIN, a personal SSN or ITIN, a state income-tax ID, and a sales tax ID.
No form ever asks for a “tax ID” without context. A bank form means the federal EIN. A state payroll form means the state number. A W-9 means the federal number of the entity on line 1. The word is the same; the number changes with who is asking.
Federal business tax ID
This is the EIN under another name. Federal tax ID, business tax ID, employer identification number, and federal employer identification number all point to the same 9 digits on the same CP-575 letter. A bank, a payment processor, and a W-9 that ask for a federal tax ID want this number.
Personal tax ID
A personal tax ID is the SSN or the ITIN. It identifies an individual on a personal return, not a business. A sole proprietor with no employees reports under an SSN, so people call that SSN their tax ID, and it is not an EIN.
State tax ID
A state tax ID, also called a state employer ID or state withholding number, registers a business for state income-tax withholding or unemployment tax. It is issued by the state, not the IRS, and it is a different number from the federal EIN. A business with employees needs both.
Sales tax ID
A sales tax ID, also called a seller's permit, resale certificate number, or sales-and-use-tax number, authorizes a business to collect sales tax in a state. It is a state number tied to sales, not a federal EIN, and a business can hold an EIN without ever needing one.
Sources: IRS and state revenue agencies, verified July 2026.
Is a federal tax ID number the same as an EIN?
Yes. Federal tax ID number is the everyday name for the EIN. Both point to the same 9 digits issued by the IRS on Form SS-4, printed as 2 digits, a hyphen, then 7, and confirmed on 1 CP-575 letter.
Banks, payment processors, and marketplaces use the labels interchangeably: EIN, federal tax ID, business tax ID, and federal employer identification number. Each request wants the same 2-then-7 digit number. Nothing about the number changes when the label changes.
Read the synonym in full on the federal tax id number page, and see the formal category the number belongs to on the ein vs tin page.
Is a state tax ID the same as an EIN?
No. A state tax ID is issued by a state agency for state withholding or unemployment tax, and the EIN is issued by the IRS for federal purposes. They are 2 numbers from 2 governments, and both are common.
A business with employees holds both. The federal EIN goes on Form 941 and Form W-2 for federal payroll taxes. The state tax ID, sometimes called a state employer ID or a withholding account number, goes on state payroll returns. Neither one replaces the other.
The sequence matters: a state almost always requires the federal EIN first, because the state registration form asks for it. Apply for the EIN on the how to apply for an ein page before registering with the state.
Is a sales tax ID the same as an EIN?
No. A sales tax ID, also called a seller’s permit or resale number, authorizes a business to collect sales tax in 1 state. The EIN is a federal number on Form SS-4. A business can hold either, both, or the EIN alone.
The 2 numbers answer different questions. The EIN answers who the federal taxpayer is. The sales tax ID answers whether a business may collect and remit sales tax on taxable goods in a state. A consulting firm with no taxable goods holds an EIN and needs no sales tax ID at all.
Vendors sometimes ask a wholesale buyer for a “tax ID” to grant a resale exemption. That request means the state sales tax ID, not the federal EIN, even though both share the label.
Is a personal tax ID, an SSN or ITIN, the same as an EIN?
No. An SSN and an ITIN identify a person; an EIN identifies a business entity. A sole proprietor with 0 employees files under an SSN and calls it a tax ID, yet it is not an EIN and never becomes one.
The confusion runs deepest here, because a sole proprietor legitimately uses a personal number as a business tax ID. The moment a second person enters, as a partner or an employee, the EIN becomes mandatory and the personal number stops working on the business return.
A non-US founder faces the mirror image: no SSN and no ITIN, yet a business that still needs an EIN. Form SS-4 line 7b resolves it with the entry Foreign. Read the two comparisons on the ein vs ssn and ein vs itin pages.
How do you tell the 4 tax IDs apart by format?
By the digit grouping and the issuer. A federal EIN prints 2 digits, a hyphen, then 7. An SSN or ITIN prints 3, then 2, then 4. A state tax ID follows each state’s own format.
| Number | Digit grouping | Issuer | Where it appears |
|---|---|---|---|
| Federal EIN | 2 then 7 | IRS | CP-575 letter, W-9 Part I, bank file |
| SSN | 3 then 2 then 4 | SSA | Social Security card, personal return |
| ITIN | 3 then 2 then 4, starts with 9 | IRS | CP-565 notice, personal return |
| State income-tax ID | Varies by state | State revenue or labor agency | State payroll returns |
| Sales tax ID | Varies by state | State department of revenue | Seller's permit, resale certificate |
Sources: IRS and state revenue agencies, verified July 2026.
The 2-then-7 split is the single fastest test. A number reading XX-XXXXXXX that arrived from the IRS is the EIN, no matter which of the federal labels a form printed above the box. Confirm the digits against your CP-575 on the CP-575 page.
Which tax ID does a form actually want?
It depends on who prints the form. A federal form or a bank wants the EIN. A state payroll form wants the state tax ID. A resale request wants the sales tax ID. A personal return wants the SSN or ITIN.
| The form or request | Tax ID it wants | Same as EIN? |
|---|---|---|
| Form W-9, Part I | Federal EIN of the entity | Yes |
| Business bank account | Federal EIN | Yes |
| Form 941 or W-2 payroll | Federal EIN | Yes |
| State withholding return | State income-tax ID | No |
| State unemployment tax | State employer ID | No |
| Wholesale or resale purchase | State sales tax ID | No |
| Sole proprietor personal return | SSN, or EIN by choice | Sometimes |
Source: IRS Form W-9 instructions and state agency forms, verified July 2026.
The W-9 is the highest-stakes case. The IRS matches the number in Part I against the name on line 1, and a mismatch triggers backup withholding at 24% under Internal Revenue Code section 3406. Enter the EIN beside the business name, never a state number. Read the line detail on the ein on w9 form page.
What does each tax ID cost?
The federal EIN costs $0 from the IRS and never renews. Most state tax IDs and sales tax permits also cost $0 to register. The only charge is a filing service that prepares the EIN application for you.
| EIN filed by | Price | Total turnaround | Year 2+ |
|---|---|---|---|
| Yourself, direct to the IRS | $0 | Not stated | $0 |
| ein-number.com, Standard | $69 | 2–3 weeks, filed by fax within 8 business days | $0 |
| ein-number.com, Fast | $99 | 7 business days, filed within 24 hours | $0 |
| State tax ID registration | $0 in most states | Varies by state | Varies |
The IRS fee is $0 on all 4 of its routes, and stays $0 in year 2 because an EIN never renews. State fees vary.
How do you get the EIN, the federal tax ID?
File Form SS-4 with the IRS. The IRS charges $0 and delivers the 9-digit EIN with a CP-575 confirmation letter. Line 7b accepts the entry Foreign when the responsible party holds no SSN.
Have an SSN? irs.gov, free, 15 minutes.
The IRS online tool issues the EIN in the same session at $0. Paying a service for that is paying for nothing.
No SSN? The fax route, or we file it.
The online tool closes without an SSN or an ITIN, and Form SS-4 goes by fax instead. The IRS fax line is 855-641-6935 for entities based in a US state and 855-215-1627 for international applicants. The IRS international phone line is 267-941-1099. No passport upload is involved.
The IRS charges $0 for an EIN through every method. The $69 Standard tier covers preparation with a senior error review, fax filing within 8 business days, and the EIN by email in 2–3 weeks. The $99 Fast tier files within 24 hours, 7 business days in total. You can use the accuracy-guaranteed EIN filing service or file it yourself for nothing. Estimate your delivery date on the EIN timeline estimator.