How to Get a Tax ID Number: EIN, ITIN and SSN Explained for Founders

Almost every founder we speak to arrives with the same sentence: "I just need a tax ID number." Then we ask one follow-up question — "which one?" — and the conversation slows down, because "tax ID number" is not one thing. In the United States it is a family of numbers that look similar, are issued by different offices, are used for completely different purposes, and have wildly different processing times. Choosing the wrong one costs weeks. Applying for the right one incorrectly costs even more, because the IRS rarely calls to explain what went wrong; it just sends the paperwork back, or worse, sends nothing at all while you refresh your mailbox.

This guide is the version of the conversation we wish every founder could have before they file anything. It covers what each number does, who qualifies, how the applications actually work in practice (not just in the instructions), and how to sequence everything so your company can open a bank account, pay contractors, collect payments and file returns without a single avoidable delay.

The Three Numbers, In One Breath

A Taxpayer Identification Number (TIN) is the umbrella term. Underneath it sit three numbers that matter to business owners.

An EIN (Employer Identification Number) identifies a business. It is nine digits, formatted 12-3456789, issued by the IRS, and free. Despite the word "employer," you need one even if you will never hire a single person. Banks ask for it. Stripe asks for it. Amazon, payroll providers, state tax agencies and your accountant all ask for it.

An SSN (Social Security Number) identifies a US person — a citizen or someone with work authorization. It is issued by the Social Security Administration, not the IRS, and it is used for personal tax filing, employment and credit.

An ITIN (Individual Taxpayer Identification Number) identifies an individual who has a US tax obligation but cannot get an SSN. It always begins with a 9. Non-resident owners of US LLCs, foreign partners in US partnerships, and people claiming treaty benefits are the usual applicants.

Here is the sentence that saves people the most time: your company gets an EIN; you personally get an SSN or, if you are not eligible for one, an ITIN. They are not alternatives to each other. Many non-resident founders end up needing both — an EIN for the company and an ITIN for themselves — but rarely at the same moment, which matters for sequencing.

Do You Actually Need an EIN?

You need an EIN if any of the following is true, and for most real businesses at least one is: you formed a corporation or a multi-member LLC; you want a US business bank account; you will hire employees or run payroll; you will file excise, employment or partnership returns; you will register for sales tax in any state; or you want to keep your personal SSN off vendor forms.

Single-member LLCs with no employees are the only common case where an EIN is technically optional for federal income tax purposes — the entity is disregarded and profits flow to the owner's personal return. In practice this exception is almost useless, because no US bank will open a business account without one, and putting your SSN on every W-9 you send is not a habit worth forming. Get the EIN.

If you have not incorporated yet, do that first. The IRS asks for your legal entity name, formation state and formation date, and issuing an EIN against a company that does not exist yet creates a mismatch you will spend months untangling. If you are still deciding where to file, our breakdown of US state filing and renewal fees shows what each state actually costs in year one and every year after, and Bizvee's company formation services handle the filing itself.

How to Get an EIN, Realistically

There are three routes, and the one available to you depends entirely on whether the responsible party — the human being who controls the entity — has an SSN or ITIN.

Route one: the IRS online application. If the responsible party has an SSN or ITIN, you complete the online interview on the IRS website during operating hours and receive the EIN immediately at the end of the session. Download the CP 575 confirmation notice before you close the tab. The IRS does not email it and re-requesting it later takes weeks.

Route two: fax. If the responsible party is a foreign person with no SSN or ITIN, the online route is closed. You complete Form SS-4, leave the responsible party's TIN field marked "Foreign," and fax it to the IRS. Turnaround is typically a few business days to four weeks. Include a return fax number, because that is how the notice comes back fastest.

Route three: mail. Same form, slower. Four to eight weeks is normal, longer during filing season. Use this only if fax is genuinely unavailable to you.

Whichever route you take, the details that get applications rejected are boringly consistent. The entity name on Form SS-4 must match the formation documents character for character, including "LLC" versus "L.L.C." The responsible party must be a natural person with real control, not a nominee, not a formation agent, and not another company. The reason for applying must be sensible — "Started new business" for a new entity, "Banking purpose" only when that is literally true. And you may only request one EIN per responsible party per day, so batching applications for multiple entities does not work.

If you would rather not manage the fax queue and the follow-ups, our EIN application service files it for you, tracks the IRS response, and delivers the CP 575 in a format banks accept.

The ITIN: When You Need One and When You Do Not

The most common misconception we correct is founders thinking they need an ITIN before they can get an EIN. You do not. An EIN can be issued to a company whose responsible party has no US tax number at all — that is exactly what the "Foreign" designation on Form SS-4 exists for. Waiting for an ITIN before applying for an EIN adds three months to your launch for no reason.

You need an ITIN when you personally have a US filing requirement. In practice that means: you are a partner in a US partnership or multi-member LLC that generates US-source income; you own a single-member LLC that is engaged in a US trade or business and must file Form 1040-NR; you need to claim a tax treaty benefit to reduce withholding; you are receiving royalty, rental or certain platform income subject to withholding; or a US institution has asked you for a W-8BEN with a TIN on it.

The application is Form W-7, and unlike the EIN it is not something you can casually mail. The IRS needs to verify your identity, which means one of three things: mailing your original passport (nobody should do this), visiting an IRS Taxpayer Assistance Center in person, or working with a Certifying Acceptance Agent (CAA) who verifies your original documents and certifies copies so your passport never leaves your hands. In nearly every case, W-7 must also be attached to a valid federal tax return unless you qualify for a specific exception — treaty benefits and third-party withholding are the two exceptions founders most often meet.

Realistic timeline: seven to fourteen weeks from a clean submission, longer if you apply between January and April when the IRS is buried in filing season. Apply in the autumn if you can. Bizvee's ITIN application service runs through a Certifying Acceptance Agent, which is the single biggest predictor of an application being accepted on the first attempt.

What Comes After the Number

The EIN is not the finish line; it is the key that unlocks the next four things.

Banking. US banks want the CP 575 or an IRS 147C letter, your formation documents, an operating agreement or bylaws, proof of address, and identification for every beneficial owner. Non-resident founders usually go the fintech route, and our banking guide walks through which providers actually onboard foreign-owned entities.

State tax registration. An EIN is federal. Selling taxable goods or services means separate state registration, and that is a different number entirely — a sales tax permit or seller's permit. We cover the mechanics in our sales tax registration service.

Payroll and contractors. Hiring US employees means state withholding accounts on top of the EIN. Paying contractors means collecting W-9s (for US persons) or W-8BENs (for foreign persons) before you send the first payment, not in January when 1099s are due.

Bookkeeping and filings. The EIN is what ties every filing together. Clean books from day one make the annual return a two-hour exercise rather than a two-week archaeology project — which is exactly what our bookkeeping service is built to prevent.

Five Mistakes We See Every Single Month

Paying for an EIN. The IRS charges nothing. You may reasonably pay a service to file it correctly and chase the response, but no one should tell you the number itself has a government fee.

Listing the wrong responsible party. Naming an agent, an accountant or a parent company invalidates the application and, if it slips through, creates an entity the IRS cannot properly associate with you.

Applying before the entity exists. The formation date on the SS-4 must be real. Filing early creates a record mismatch that surfaces later, usually at the worst possible time — during bank onboarding.

Requesting a second EIN instead of fixing the first. If you lose the number, request a 147C letter. A duplicate EIN means two tax records for one company and two sets of filing obligations.

Assuming the EIN makes you tax-resident, or that it makes you compliant. It does neither. It is an identifier, not a status and not a filing. Foreign-owned single-member LLCs, for example, still owe Form 5472 with a pro-forma 1120 every year — with penalties starting at $25,000 for missing it.

A Sequence That Works

If you are starting from zero, this order avoids every dependency trap: form the entity and get your formation documents; apply for the EIN immediately, using "Foreign" for the responsible party if you have no SSN or ITIN; open banking and payment processing with the EIN in hand; register for sales tax in states where you have nexus; set up bookkeeping before you have transactions to reconstruct; and apply for your personal ITIN when your first US filing obligation is actually on the horizon, not before.

Done in that order, most founders are operational within a fortnight of incorporation, with the ITIN arriving quietly in the background months later — long before it is ever needed.

If you want the whole sequence handled as one project rather than five separate errands, talk to a Bizvee specialist. We file the entity, chase the EIN, run the ITIN through a Certifying Acceptance Agent, and hand you a company that is ready to bank, bill and file.