EIN vs ITIN vs SSN: the US tax identification numbers explained

9 digits and is issued in 7 to 11 weeks. EIN, ITIN, SSN, US tax identification numbers can be confusing. Here is a clear guide on what each is and when you need them.

The ITIN has 9 digits and is issued in 7 to 11 weeks, while the SSN has 9 digits and is granted only to US legal residents.

EIN, ITIN, SSN. US tax identification numbers can be confusing. Here's a clear guide to what each one is, whether you need them, and how to get them.

Social Security Number (SSN)

An SSN is the personal tax identification number for US citizens and certain US residents (green card holders, some visa holders).

Format: XXX-XX-XXXX

Who needs it: US citizens and eligible US residents.

Do you need one? As a non-resident LLC owner, you almost certainly don't have an SSN and don't need one for your LLC operations. The SSN is not required for forming an LLC, opening Mercury, or filing Form 5472.

Employer Identification Number (EIN)

The EIN is the business tax ID for your LLC. essential for every aspect of LLC operation. Think of it as your company's Social Security Number.

Format: XX-XXXXXXX

Who needs it: Every US business entity, including every LLC.

Do you need one? YES. absolutely required. Without an EIN, you cannot:

Open a bank account (Mercury, Relay)
File IRS forms (Form 5472, Form 1120)
Set up Stripe or PayPal Business
File the BOI Report with FinCEN
Work with US clients (they need your EIN for W-8BEN-E)

How to get it: At Exentax, we obtain your EIN as part of the formation package. For non-residents, the process involves filing Form SS-4 with the IRS (4-8 weeks by mail, faster by fax). You cannot apply online without a US SSN or ITIN.

The EIN confirmation letter (CP 575): Once approved, the IRS sends this letter confirming your EIN. Mercury specifically requests it. Keep it safe. digital and physical copies.

Individual Taxpayer Identification Number (ITIN)

An ITIN is issued by the IRS to individuals who need to file US tax returns but don't have (or aren't eligible for) an SSN.

Format: 9XX-XX-XXXX (always starts with 9)

Do you need an ITIN as a non-resident LLC owner?

Probably not, for most of our clients. If your LLC has no US-source income and you're not filing a US personal tax return, you typically don't need an ITIN.

When you might need an ITIN:

PayPal Business requires the owner's ITIN for personal identity verification (in addition to the LLC's EIN)
Your LLC has US-source income and you need to file Form 1040-NR personally
Specific treaty benefit claims that require personal filing
Applying for certain US financial products that require personal tax ID

How to get an ITIN:

File Form W-7 with supporting documents
Must be submitted with a US tax return or a certified exception
Processing time: 7-11 weeks (sometimes longer)
Requires certified copies of identification documents (passport)
Can be filed through a Certifying Acceptance Agent (CAA) who can verify your documents

Important ITIN notes:

ITINs expire if not used on a federal tax return for 3 consecutive years
Renewal requires the same process as initial application
The ITIN is for tax purposes only, not a work permit or immigration status

Summary table

Common confusion points

"Do I need an ITIN to form an LLC?" No. You need an EIN (for the LLC), not an ITIN (for you personally).

"Mercury requires my SSN." No. Mercury accepts non-US residents without SSN. You provide your passport and foreign tax ID instead.

"PayPal won't let me register without SSN/ITIN." PayPal Business may require the owner's ITIN. If PayPal is essential for your business, we can guide you through the ITIN application process.

"Can I use my EIN instead of ITIN?" No. they serve different purposes. EIN identifies your business. ITIN identifies you personally. Some platforms need both.

The complete tax ID comparison

When your LLC needs an ITIN (and when it doesn't)

You need an ITIN if:

You want to use PayPal Business (requires owner's ITIN)
You sell on Amazon.com as a third-party seller (requires ITIN for tax reporting)
You have US-source income subject to withholding (royalties, rents)
You want to file a US personal tax return (rare for non-residents)

You do NOT need an ITIN if:

You use Mercury for banking (EIN is sufficient)
You use Stripe for payments (EIN + passport is sufficient)
You use Wise Business for currency conversion (EIN is sufficient)
You have no US-source income (most digital service providers)
You don't sell on US marketplaces

How to get an ITIN

Complete IRS Form W-7
Attach a valid federal tax return (or qualify for an exception)
Include certified passport copies or use a Certifying Acceptance Agent (CAA)
Mail to IRS ITIN Operations, Austin, TX
Wait 7-11 weeks for processing

At Exentax, we can coordinate ITIN applications for clients who need them, working with Certifying Acceptance Agents so you never have to mail your original passport.

Frequently asked questions

How long does each ID take to obtain?

Can I start my LLC before getting the EIN?

Yes. The LLC is formed first (state filing), then the EIN is applied for. You can't open bank accounts until the EIN is received, but the LLC legally exists from the moment the state approves the Articles of Organization.

What if my EIN letter (CP 575) gets lost?

You can request a replacement from the IRS by calling the International line. Alternatively, Exentax can request a verification letter (147C letter) that serves the same purpose. Your EIN number itself never changes.

Can I use my foreign tax ID instead of an ITIN?

For most LLC operations, yes. Mercury accepts foreign tax IDs. Stripe accepts passport numbers. The EIN covers the LLC's identity. An ITIN is only needed for specific platforms (PayPal, Amazon) that require personal US tax identification.

Does the EIN expire?

No. Once issued, an EIN is permanent. it never expires and never changes. Even if you dissolve the LLC, the EIN remains associated with it in IRS records.

Can I have multiple EINs?

Each LLC gets exactly one EIN. If you have multiple LLCs, each one has its own EIN. You cannot share EINs between entities.

To keep going on this thread, Common LLC problems and how to avoid them: lessons from real clients fills in a nuance this guide only touched on.

Legal and regulatory references

This article relies on rules currently in force. Main sources for verification:

United States. Treas. Reg. §301.7701-3 (entity classification / check-the-box); IRC §882 (tax on foreign income effectively connected with a US trade or business); IRC §871 (FDAP and withholding on non-residents); IRC §6038A and Treas. Reg. §1.6038A-2 (Form 5472 for 25% foreign-owned and foreign-owned disregarded entities); IRC §7701(b) (tax residency, substantial presence test); 31 U.S.C. §5336 (Corporate Transparency Act, BOI Report to FinCEN).
Spain. Law 35/2006 (LIRPF), arts. 8, 9 (residency), 87 (income attribution), 91 (CFC for individuals); Law 27/2014 (LIS), art. 100 (CFC for companies); Law 58/2003 (LGT), arts. 15 (anti-abuse) and 16 (simulation); Law 5/2022 (Form 720 penalty regime after CJEU C-788/19 of 27/01/2022); RD 1065/2007 (Forms 232 and 720); Order HFP/887/2023 (Form 721 crypto). We close it with you from Exentax: one call, the filing goes out, the archive is set, and the risk stays on paper.
Spain–US treaty. BOE of 22/12/1990 (original DTT); Protocol in force since 27/11/2019 (passive income, limitation on benefits).
EU / OECD. Directive (EU) 2011/16, amended by DAC6 (cross-border arrangements), DAC7 (Directive (EU) 2021/514, digital platforms) and DAC8 (crypto-assets); Directive (EU) 2016/1164 (ATAD: CFC, exit tax, hybrid mismatches); OECD Common Reporting Standard (CRS).
International framework. OECD Model Convention, art. 5 (permanent establishment) and Commentaries; BEPS Action 5 (economic substance); FATF Recommendation 24 (beneficial ownership).

Applying any of these rules to your specific case depends on your tax residency, the LLC's activity and the documentation you keep. This content is informational and does not replace personalized professional advice.

Next steps

Now that you have the full context, the natural next step is to map it against your own situation: what fits, what doesn't, and where the nuances depend on your residency, your activity and your volume. A quick review of your specific case usually saves a lot of noise before taking any structural decision.

Banking and tax facts worth clarifying

Fintech and CRS information evolves; here is the current state:

Before going further, put numbers on your case: the Exentax calculator compares, in under 2 minutes, your current tax bill with what you would carry running a US LLC properly declared in your country of residence.

> Talk to our team

Notes by provider

Mercury operates with several federally chartered partner banks and FDIC coverage via sweep network: mainly Choice Financial Group and Evolve Bank & Trust, with Column N.A. still in some legacy accounts. Mercury is not itself a bank; it is a fintech platform backed by those partner banks. If Mercury closes an account, the balance is typically returned by paper check mailed to the account holder's registered address, which can be a serious operational problem for non-residents; keep a secondary account (Relay, Wise Business, etc.) as contingency.
Wise ships two clearly different products: Wise Personal and Wise Business. For an LLC you must open Wise Business, not the personal account. Important CRS nuance: a Wise Business held by a US LLC sits outside CRS because the account holder is a US entity and the US is not a CRS participant; the USD side operates via Wise US Inc. (FATCA perimeter, not CRS). In contrast, a Wise Personal opened by an individual tax-resident in Spain or another CRS jurisdiction does trigger CRS reporting via Wise Europe SA (Belgium) on that individual. Opening Wise for your LLC does not bring you into CRS through the LLC; a separate Wise Personal in your own name as a CRS-resident individual does report.
Wallester (Estonia) is a European financial entity with an EMI/issuing-bank licence. Its European IBAN accounts are within the Common Reporting Standard (CRS) and therefore trigger automatic reporting to the tax administration of the holder's country of residence.
Payoneer operates through European entities (Payoneer Europe Ltd, Ireland) that are also in scope for CRS for clients resident in participating jurisdictions.
Revolut Business: when paired with a US LLC, it operates under Revolut Technologies Inc. with Lead Bank as its US banking partner. The account delivered is a US account (routing + account number); no European IBAN is issued to a US LLC. The European IBANs (Lithuanian, Belgian) belong to Revolut Bank UAB and are issued to European clients of the group. If you are offered a European IBAN tied to your LLC, confirm exactly which legal entity holds that account and which regime it reports under.
Zero tax: no LLC structure delivers "zero tax" if you live in a country with CFC/tax transparency or income attribution rules. What you achieve is no double taxation and correct reporting at residence, not elimination.

ITIN and SSN: what they are, how they differ and which one you should apply for

Mixing up ITIN and SSN is one of the most common mistakes when setting up an LLC without a US passport. They are two tax numbers issued by different administrations, with very different use cases. Here is the clear breakdown so you know which to request, when and how.

SSN (Social Security Number). Issued by the Social Security Administration and reserved for US citizens and residents with work authorisation (H1B, L1, permanent residents, etc.). If you are none of those, you cannot get an SSN - not a procedure, an immigration requirement. Without SSN it does not close: there is an alternative.
ITIN (Individual Taxpayer Identification Number). Issued by the IRS for non-resident individuals with US tax obligations (filing 1040-NR, opening certain accounts, receiving 1099 with withholding). Applied with form W-7 + certified or notarised passport + document showing the tax need (e.g. form 1042-S, 1099, pending return).
When you need neither for your LLC. Single-member LLC without ETBUS, EIN obtained via SS-4 (which accepts "Foreign" in place of SSN/ITIN), Mercury onboarded without ITIN: this is the standard path for a non-resident running international B2B. Don't force ITIN if your activity does not require it.
When you do need ITIN. Selling on Amazon US or platforms that withhold 30% without TIN, royalty beneficiary with 1042-S, filing personal 1040-NR (rare for non-resident without ETBUS), or specific bank accounts that demand it.

What we are asked the most

Does my LLC need SSN or ITIN to open Mercury? Neither. Mercury uses the LLC's EIN and the owner's passport. If a provider asks you for it, it is using a US-domestic flow - request the international version or change provider.

How long does it take to get an ITIN? 6-12 weeks directly with the IRS by mail + certified passport. With a Certified Acceptance Agent (CAA) the passport stays with you and the timeline is similar.

At Exentax we first evaluate whether you actually need an ITIN - and if yes, we handle it end to end (W-7 + documentation + follow-up) without you having to mail your passport.

Legal & procedural facts

FinCEN and IRS reporting requirements moved recently; the current state is:

BOI / Corporate Transparency Act: your LLC is NOT required to file (a competitive advantage). After FinCEN's March 2025 interim final rule, the BOI Report obligation was narrowed to "foreign reporting companies" (entities formed OUTSIDE the US and registered to do business in a state). A US-formed LLC owned by a non-resident does NOT file the BOI Report: one fewer filing on your calendar, less paperwork, and a cleaner structure than ever. If your LLC was formed before March 2025 and you already filed BOI, keep the acknowledgement. The regulatory status can change again: we monitor FinCEN.gov on every filing and, if the obligation comes back, we handle it at no extra cost. Current status verifiable at fincen.gov/boi.
Form 5472 + pro-forma 1120. For a Single-Member LLC owned by a non-resident, the final regulations of Treas. Reg. §1.6038A-1 (in force since 2017) treat the LLC as a corporation for 5472 purposes. Procedure: pro-forma Form 1120 (header only: name, address, EIN, tax year) with Form 5472 attached. It is filed by certified mail or fax to the IRS Service Center in Ogden, Utah, not e-filed via standard MeF. Due date: April 15; extension via Form 7004 to October 15. Penalty: $25,000 per form per year, plus $25,000 per additional 30 days of non-filing after IRS notice.
Substantive Form 1120. Only applies if the LLC has filed a check-the-box election to C-Corp (Form 8832): it then pays 21 % federal corporate tax and files a substantive 1120. A standard disregarded LLC does not file a substantive 1120 and does not pay federal corporate tax.
EIN and notice. Without an EIN you cannot file 5472 or BOI. The IRS does not warn before imposing penalties; you find out when an EIN is flagged or a later filing is rejected. At Exentax we have closed clients in exactly this spot at zero penalty. Speaking up early pays off — and saves you five figures.

Who needs an ITIN?

Field note from running this for clients month after month: the rule is straightforward, the execution is where it breaks. Plan the operational side before the legal side.

ITIN vs SSN: key differences

The numbers and the calendar matter - get either wrong and the rest unravels.

Why you need an ITIN if you own an LLC

Step 1: Prepare Form W-7

Most of the avoidable damage we see in this exact point comes from skipping the documentation step, not from the underlying tax logic.

Step 2: Gather supporting documentation

If it is not clean here, every downstream assumption becomes negotiable in front of the authority.

Step 3: Include a tax return

Most of the avoidable damage we see in this exact point comes from skipping the documentation step, not from the underlying tax logic.

Want to discuss it now? Message us on WhatsApp and we'll get back to you today.

If you don't have an ITIN yet, see our service guide get your ITIN step by step and start the filing today.

Or call us directly at +34 614 916 910 if you'd rather talk.

For state-specific details, see our Wyoming LLC service page with closed costs and timelines.

On the same topic

We file your ITIN with the IRS through a Certifying Acceptance Agent — your original passport stays with you. Get my ITIN.