TIN vs EIN for an LLC: Taxpayer ID, Federal Tax ID, and SS-4 Untangled

What Is the Difference Between a TIN and an EIN?

TIN is the IRS umbrella term covering 5 taxpayer IDs: EIN, SSN, ITIN, ATIN, and PTIN. EIN is the 9-digit federal ID for a US business. Every EIN is a TIN, but not every TIN is an EIN.

The IRS defines TIN in Internal Revenue Code section 6109 as any identifying number used on a federal return. That definition sweeps up 5 IDs. For an LLC, only 3 of the 5 actually matter: EIN for the business, SSN for a US-citizen owner filing personally, and ITIN for a non-US owner filing personally. ATIN is for adopted children, PTIN is for paid tax preparers. Neither touches an LLC's own filings.

The confusion is a vocabulary problem, not a numbering problem. TIN is a category, and EIN is 1 member of that category. Asking whether an LLC needs a TIN or an EIN is like asking whether it needs a vehicle or a truck. A form that asks for a Taxpayer Identification Number from an LLC is asking for the EIN.

3 facts settle most of the confusion. All 5 TIN types are 9 digits except the PTIN, which is a letter plus 8 digits. The IRS issues 4 of the 5 at $0. And an LLC holds exactly 1 entity-level federal number for its whole life, no matter how many different names a form uses to ask for it.

How Does TIN Cover EIN, SSN, and ITIN for an LLC Founder?

EIN, SSN and ITIN are all 9-digit federal IDs sitting under the TIN umbrella. EIN identifies a business, SSN identifies a US citizen or permanent resident, ITIN identifies a non-US individual. The IRS accepts each in a different place on Form W-9.

Source: IRS Publication 1635 and Internal Revenue Code section 6109, verified July 2026.

Only 3 of the 5 reach an LLC founder. The EIN is the entity number and belongs to the LLC itself. The SSN and the ITIN belong to a person, and they enter an LLC's paperwork only where a human signs: the responsible party on Form SS-4 line 7b, or a Form W-9 signed by a disregarded-entity owner.

The PTIN is the 1 entry in the table that costs money and the 1 that never appears on an LLC filing. It identifies a paid preparer who signs a return on the LLC's behalf, and it sits in the preparer block rather than the entity block. An LLC that files its own returns encounters 0 PTINs.

Format alone resolves most questions. A 9-digit number starting with 9 is an ITIN and belongs to a person. A 9-digit number in a 3-2-4 pattern is an SSN. A 9-digit number in a 2-7 pattern is the LLC's EIN.

Which 6 Names Point to the Same 9-Digit LLC Number?

Taxpayer ID, Tax Payer Number, Taxpayer Identification Number, Federal Tax ID, Federal EIN, and Employer Identification Number. All 6 mean the LLC's EIN in 99% of cases.

Source: IRS Form SS-4 and IRS Publication 1635, plus bank onboarding documents, verified July 2026.

The 6 labels are not a naming problem so much as a source problem: each one comes from a different organisation writing about the same 9 digits. The IRS uses EIN and Employer Identification Number. Banks print Federal EIN on onboarding forms. Vendors ask for a Federal Tax ID on a W-9 request. State agencies write Taxpayer ID or Tax Payer Number. None of the 6 is wrong, and none of them signals a second number that the LLC is supposed to have. An LLC holds exactly 1 entity-level federal number, and every request in the table above is asking for that same one.

Which TIN Does Your LLC Use for Federal Tax Filings?

Match by structure. Multi-member LLC: EIN, always. Foreign-owned single-member LLC: EIN, always. US-owned single-member LLC: SSN or EIN, at the owner's choice.

Form 1065 for a partnership carries the LLC's EIN in the entity box. Form 5472 for a foreign-owned disregarded entity carries the EIN too, with a pro-forma Form 1120 attached. A US-owned single-member LLC that has 0 employees files on Schedule C of the owner's Form 1040 under the owner's SSN, or on the LLC's EIN if the owner obtained one. The choice affects 0 tax dollars but affects which TIN goes on the W-9 to every US client.

The rule follows the tax classification, not the state paperwork. An LLC taxed as a partnership or a corporation is a separate filer, so it uses its own EIN with no exception. An LLC treated as a disregarded entity has no separate return, so the owner's number carries the income instead.

The 1 case founders get wrong is the foreign-owned single-member LLC. It is a disregarded entity for income tax, which suggests the owner's number. It still needs its own EIN, because Form 5472 and the pro-forma Form 1120 are entity filings and a non-US owner has no SSN to substitute.

Full match on EIN for a single-member LLC and EIN for a multi-member LLC.

When Does Taxpayer ID Not Mean the EIN for an LLC?

3 cases. A US-owned single-member LLC without an EIN uses the owner's SSN. A non-US individual filing personally uses an ITIN. A sole proprietor without any LLC uses the SSN. All 3 attach to a person, not the entity.

The 1st case matters most for LLC founders. A US-owned single-member LLC that has 0 employees and 0 excise tax is legally allowed to skip the EIN and file on the owner's SSN, under 26 CFR § 301.7701-2. In that case the Taxpayer ID that goes on Form W-9 is the SSN. Every US bank still requires the 9-digit EIN, so most owners obtain one anyway. See does a single-member LLC need an EIN for the trigger list. The 2nd case matters for foreign owners filing personal ITIN returns. The 3rd case does not touch LLCs at all.

A 4th case looks like an exception and is not one. A state comptroller asking an LLC for its taxpayer number wants the state registration number, not the federal EIN. Texas issues 11 digits and California issues 12, and neither is a TIN under section 6109. The issuing agency settles which number is wanted.

Is the State Tax ID the Same as the Federal Tax ID for an LLC?

No. Federal Tax ID is a federal number, always. States issue separate state tax IDs through the state Department of Revenue or Franchise Tax Board. Fees range from $0 to $300 depending on the state.

California issues a state tax ID through the Franchise Tax Board, and the minimum franchise tax on an LLC is $800 a year. New York issues a state tax ID through the Department of Taxation and Finance. Texas issues a state tax ID through the Comptroller of Public Accounts, and the state franchise tax starts above $2.47 million in revenue. All 3 numbers are different from the federal EIN, and none of the 3 replaces it on a W-9 or a bank application.

The 2 numbers do different jobs. The federal EIN handles federal income tax, payroll tax and every federal information return. A state tax ID handles sales tax collection, state payroll withholding and state income or franchise tax. An LLC selling into 3 states holds 1 EIN and up to 3 state registrations.

Sequence matters at registration. Most states ask for the federal EIN on the state application, so the EIN comes first and the state number second. An LLC that applies to a state before holding its EIN stalls at that field. See how to get an EIN for an LLC for the federal step.

What Is the Difference Between the SS-4, the EIN, and the CP-575?

3 different things. SS-4 is the 2-page application form. The EIN is the 9-digit number the IRS assigns from it. CP-575 is the 1-page letter that proves the assignment. Only 1 of the 3 is a number.

Form SS-4 carries 18 lines, and only 7 of them change based on LLC facts: 1, 4a, 4b, 7a, 7b, 8b, and 9a. The IRS last revised it in December 2019, and that revision remains current for 2026. It is filed through 1 of 4 channels: online, fax to 855-641-6935, mail, or the international phone line at 267-941-1099. Line-by-line prep sits on the LLC EIN application walkthrough.

The SS-4 never carries the EIN, because the EIN does not exist until the IRS processes the form. That is why banks and vendors ask for the CP-575, not the SS-4. The CP-575 carries the 9-digit EIN, the LLC's legal name from line 1, and the responsible party from line 7a, and the IRS prints it exactly 1 time. If it is lost, the 147C letter is the free replacement. See the LLC CP-575 letter and the EIN verification letter. The EIN itself never renews, and no filing service charges an annual renewal, because nothing renews.

Source: IRS Instructions for Form SS-4, verified July 2026.

How Often Does an LLC File the SS-4?

1 time, for the life of the LLC. The EIN never expires, never renews, and carries no annual fee. An LLC files a 2nd SS-4 in exactly 4 situations, all of them structural.

The 4 triggers for a 2nd EIN: a single-member LLC adds a member and becomes a partnership; a multi-member LLC drops to 1 member and becomes a disregarded entity; the LLC is taken through bankruptcy proceedings; or a new legal entity is formed and the old one dissolved. A name change is not a trigger. A move between states is not a trigger. Electing corporate treatment on Form 8832 is not a trigger, and neither is an S-corporation election on Form 2553. See when an LLC needs a new EIN and LLC name change and the EIN.

Any service that bills an LLC a yearly amount to “maintain” or “renew” a Taxpayer ID is charging for nothing. The IRS has issued more than 100 million EINs since 1974 and has never charged a renewal on any of them. The 147C replacement letter is also $0, by phone, at 800-829-4933.

Source: IRS — Do You Need a New EIN?, verified July 2026.

Can 1 LLC Hold 2 Federal Tax IDs?

No, not at the same time. 1 legal entity holds exactly 1 active EIN. Duplicate EINs happen when an owner applies twice, and the IRS deactivates the surplus number on request.

A duplicate is common when an online application times out and the owner refiles. The IRS assigns a 2nd number, and both appear valid until the owner writes to the IRS Business and Specialty Tax Line asking which to retain. The IRS keeps the number already tied to filed returns and closes the other. Filing 2 sets of returns under 2 EINs for 1 LLC produces mismatch notices, and the resolution runs 6 to 8 weeks.

A separate case is 1 owner holding several LLCs. Each LLC is its own legal entity, so each needs its own EIN — 5 LLCs means 5 EINs, filed on 5 separate SS-4 forms. A registered series LLC raises the same question per protected series. See EIN for a series LLC.

A 3rd case looks like 2 federal IDs and is not. An LLC holds 1 EIN and its owner holds 1 SSN or ITIN. Both are federal 9-digit numbers, and both appear across the LLC's paperwork. They identify 2 different taxpayers, so holding both is the normal state rather than a duplicate.

How Do You Verify an LLC's Taxpayer ID with the IRS?

1 route: call the IRS Business and Specialty Tax Line at 800-829-4933, Monday to Friday, 7am to 7pm local time. The IRS confirms the EIN to the responsible party on Form SS-4 line 7a and mails a 147C letter.

The IRS runs no public EIN lookup. There is no free national registry that returns a private company's Taxpayer ID from a business name, and every site advertising one is either reselling SEC EDGAR data for public filers or reselling IRS Publication 78 data for registered non-profits. Both of those sources are free and cover only entities that are already public record. Full detail on the LLC EIN number lookup and recovering a lost LLC EIN.

The 147C arrives by mail in 7 to 10 business days, or by fax the same day if the caller supplies a fax number during the call. It carries the same 9 digits as the original CP-575, and US banks accept it in place of the CP-575 at account opening.

The caller has to be authorised. The IRS releases an LLC's EIN to the responsible party named on Form SS-4 line 7a, to a corporate officer or member of record, or to a third party holding a signed Form 2848 or Form 8821. A caller outside those 3 categories is refused.

Do Foreign Owners of a US LLC Need Both an EIN and an ITIN?

Yes in most cases. The LLC uses its own EIN. The foreign individual owner uses an ITIN if they file US personal returns, or nothing if the LLC's own filings cover the tax obligation entirely.

A foreign-owned single-member LLC files Form 5472 and a pro-forma Form 1120 every year, both under the LLC's EIN. The $25,000 penalty for missing that return sits on the LLC, not the individual owner. See Form 5472 and EIN for a foreign-owned LLC for the full calendar. An ITIN takes 8 to 12 weeks to issue after Form W-7 is filed with a signed personal return.

The 2 numbers are obtained on different tracks, and only 1 of them is required to start. The EIN comes from Form SS-4, needs no SSN, and issues in 4 to 7 business days by fax on 855-215-1627. Line 7b accepts the entry Foreign in place of a US number, so a non-US owner applies without holding an ITIN.

An ITIN becomes necessary only when the owner personally files a US return, which happens when the LLC is engaged in a US trade or business or the owner claims a treaty position. A foreign owner whose LLC only files Form 5472 and the pro-forma Form 1120 needs 0 ITINs. See LLC EIN without an SSN.

Which TIN Goes on Form W-9 for an LLC Founder?

Exactly 1 of 2 boxes: SSN or Employer Identification Number. A US-owned single-member LLC without an EIN writes the owner's SSN. Every other LLC writes the EIN. Never both.

Line 1 of Form W-9 shows the legal name. Line 2 is optional for the business name if different. The middle box carries 2 numbered slots: Social Security Number on top and Employer Identification Number below. A W-9 that carries both numbers is rejected by most US payers, because the IRS instructions require the signer to pick 1. See what is a disregarded entity for the classification behind that pick.

Line 3a carries the classification checkbox, and an LLC has 3 options there: C for corporation, S for S-corporation, or P for partnership, written into the box marked “LLC.” A US-owned single-member LLC treated as disregarded checks the individual box instead, not the LLC box, and enters the owner's name on line 1. That single instruction accounts for a large share of rejected W-9s, because the LLC name on line 1 with an SSN below it fails the IRS name-and-number match.

A failed match triggers a CP-2100 notice to the payer, and the payer then starts 24% backup withholding until the LLC returns a corrected W-9. Recovering withheld amounts means claiming them as a credit on the next annual return, so the cash sits with the Treasury for up to 12 months. Getting the number and the name to agree on the first W-9 avoids the entire cycle.

Which TIN Does a US Bank Ask an LLC For?

The EIN. Every US business bank requires the 9-digit EIN plus the CP-575 letter before opening an account. No US bank opens an LLC account on the owner's SSN alone.

Mercury, Wise, Relay, Chase, and Bank of America each pull the EIN from the CP-575 at onboarding. The match runs against the LLC's legal name on Form SS-4 line 1 and the responsible party on line 7a. A mismatch on either field holds the account application for 5 to 10 business days. See EIN for an LLC bank account for the full onboarding walk.

The requirement comes from the bank, not the IRS. Federal customer identification rules oblige a bank to collect a taxpayer identification number for every business customer, and every US bank reads that as the EIN for an LLC. No federal statute forces a US-owned single-member LLC to hold an EIN, so this is the trigger that decides the question in practice.

Banks ask for 3 things beyond the number: the CP-575 or a 147C letter, the state-stamped Articles of Organization, and identification for each owner above 25%. The EIN alone opens 0 accounts. A name that reads differently across those 3 documents is the most common reason an application stalls.

Which ID Does Each Form and Counterparty Actually Want?

14 common requests, 3 possible answers: the EIN, the owner's SSN, or the owner's ITIN. The EIN answers 11 of the 14. The label on the request is the wrong thing to read; the counterparty is the right thing to read.

The 1 row that trips founders is Schedule C. A US-owned single-member LLC with 0 employees reports on the owner's Form 1040, and the IRS accepts the owner's SSN there even when the LLC holds an EIN. That is the disregarded-entity treatment described in what is a disregarded entity. It changes which number the return carries; it changes 0 dollars of tax.

Source: IRS Form W-9 and its instructions, verified July 2026.

Which Term Does the IRS Use Officially?

EIN on Form SS-4. Employer Identification Number on the CP-575 letter. TIN as the umbrella term in 26 U.S.C. § 6109. The IRS uses Taxpayer ID on 0 forms.

Every IRS letter and form the LLC receives uses 1 of 3 official terms: EIN, Employer Identification Number, or TIN. Third-party paperwork — bank onboarding, state agency registrations, vendor W-9 requests — uses casual synonyms like Taxpayer ID or Federal Tax ID. Match the number correctly regardless of the label, because a 1-digit mismatch delays account opening by 5 to 10 business days. Backup withholding on a mismatched W-9 runs at 24% under 26 U.S.C. § 3406, and the payer holds the withheld amount for up to 21 days.

The IRS itself is not fully consistent, which is why the casual terms persist. Form SS-4 is titled Application for Employer Identification Number, the CP-575 spells out Employer Identification Number, and the W-9 instructions use Taxpayer Identification Number for the same field. 3 IRS documents, 2 official terms, 1 number.

Employer Identification Number is the 1 term that misleads on its face. An LLC with 0 employees holds an EIN, and the number is required for a bank account, a partnership return and a Form W-9 long before any payroll exists. The name is a 1974 artefact rather than a description of who needs one.

How Much Does Each TIN Cost an LLC Owner?

$0 at the IRS for EIN, SSN, and ITIN. Only the PTIN carries a fee, at $19.75 per year, and PTIN never applies to an LLC. einforllc.co Standard is $97, Fast is $127.

The IRS has published the EIN fee as $0 since 1974. The SSN is free at the Social Security Administration on Form SS-5. The ITIN is free at the IRS on Form W-7 with a signed tax return. Only the paid tax preparer identifier (PTIN) carries a fee, and PTIN identifies a person, not a business. einforllc.co charges $97 on Standard for a filing within 7 business days, or $127 on Fast within 24 hours. Full cost detail on LLC EIN cost.

The 3 IRS channels differ in speed rather than price. The online EIN Assistant issues the number in about 15 minutes, and it is open to applicants who hold an SSN or ITIN. Fax to 855-641-6935 returns the EIN in 4 to 7 business days, and it is the route foreign owners use because it requires no SSN. Mail runs 6 to 11 weeks. All 3 cost $0.

What a paid service buys is the classification decision on line 9a, the responsible-party entry on line 7a, and the follow-up when the IRS returns a reference 101 error. Those 3 items cause most rejections, and a rejection restarts the clock. See how to get an EIN for an LLC for the channel-by-channel walkthrough.

What Else Do LLC Founders Ask About TIN vs EIN?

This page states federal tax rules current as of July 2026. It is not legal or tax advice. Confirm your LLC's position with a licensed CPA or attorney before filing.