Imagine this scenario: your client recently started working remotely for a US-based company while living abroad. They have been receiving your paychecks without any issues, but then you receive a letter from the IRS imposing heavy fines and demanding back taxes.
The reason? They didn’t obtain a US Tax ID ITIN number for non-residents, which is crucial for complying with US tax laws. This nightmare situation underscores the importance of promptly understanding and securing your ITIN application, easily.
Please note that by obtaining an ITIN does not give you US citizenship. Work with Optimise Accountants. We will show you how to apply for an ITIN from the UK for your clients.
How To Get A US Tax ID For Non-Residents
The Individual Taxpayer Identification Number (ITIN) is a crucial nine-digit processing number issued by the IRS for individuals who need to file US returns but are not eligible for a Social Security Number. For UK residents and other non-US citizens, obtaining an ITIN opens doors to legitimate business activities, property investments, and proper tax compliance.
Many individuals and businesses in the UK require a US tax ID to establish companies, purchase property, or fulfil their US tax obligations. Whether you’re working remotely for an American company, investing in American real estate, or claiming tax treaty benefits, an ITIN ensures you can meet your tax responsibilities while accessing financial services that require US identification.
Who Needs to Apply for a US Individual Tax Identification Number (ITIN) from the IRS?
An ITIN serves various purposes for non-residents conducting U.S.-related financial activities. UK residents commonly need ITINs for setting up an American businesses, buying homes in the US, managing rental income, and filing 1040 tax returns to claim treaty benefits.
If you’ve sold a US real estate property and were subject to the 15% FIRPTA withholding tax, you’ll likely need to file a 1040 return to the IRS, which requires an ITIN. Similarly, remote workers for American companies, investors in US securities, and individuals opening US bank accounts often require this tax identification number (ITIN). The ITIN also enables you to claim benefits under tax treaties, obtain mortgages for property purchases, and establish investment accounts with financial institutions. It’s important to note that obtaining an ITIN does not give you US citizenship or work authorisation in the United States. ITINs are approved by The Internal Revenue Service (IRS) via Form W-7.Application Process: Form W-7
To apply for an ITIN, you must complete Form W-7, the official IRS application. This requires personal information, including your name, birthdate, mailing address, and Foreign Tax Identification Number (FTIN) if applicable. The application also asks you to specify the reason for requesting an ITIN, such as filing a US tax return or opening a bank account.
When completing W-7, accuracy is crucial. Any errors or omissions can result in processing delays or rejection. The application must be filled out completely, with all required fields addressed. Most ITIN applications must be accompanied by a US federal tax return, though certain exceptions exist for specific circumstances like opening bank accounts or claiming treaty benefits.
Pros: Low cost; works from anywhere in the UK. Cons: Must send original passport/certified copies; risk of document loss; long processing time (7–11+ weeks). Best for: Applicants with plenty of time who want the cheapest option and don’t mind mailing originals. |
Pros: In-person verification; keep your passport; fewer errors.
Cons: Only in the US; travel costs/time; appointments required.
Best for: Applicants visiting the US who want same-day verification.
Pros: Keep your passport; expert guidance; fewer rejections; white-label services for accountants.
Cons: Service fees apply; processing still depends on IRS timeline (7–11+ weeks).
Best for: UK applicants needing security, speed, and professional help—ideal for accountants outsourcing ITIN work.
📅 Application Checklist & Timeline (UK Applicants) from our CAA Experts
| Stage & Action Steps | Timing / Tips |
|---|---|
1. Confirm ITIN Need Check if you qualify for an exception (e.g., mortgage interest reporting, scholarship) or must attach a U.S. tax return. | Day 1 – Review IRS W-7 Instructions carefully. |
2. Gather ID & Proof If not using passport, gather 2 forms of ID (e.g., UK driving licence, birth certificate). Supporting documents are essential to ensure the success of the ITIN application. | Day 1–2 – Names, DOB, and addresses must match W-7 exactly. |
3. Choose Submission Method Mail to IRS (cheapest, but originals/certified copies required). IRS TAC Office (US) if travelling there. | Day 2 – Book CAA appointment if using this route. |
4. Complete Application W-7 Tick correct Reason box (a–h). Ensure only one Reason unless dual purposes apply (attach evidence). Use US mailing address if available for faster correspondence. | Day 3 – Double-check entries for typos or inconsistencies. |
5. Prepare Tax Return (if required) Attach full, signed 1040 if no exception applies. Attach all supporting W-2/1099 schedules. | Day 3–4 – Ensure names & addresses match W-7 exactly. |
6. Certification / Mailing If mailing: send to IRS ITIN Operations, Austin TX 73301-5600, USA. | Day 4–5 – Use tracked courier if mailing originals. |
7. Wait for IRS Processing Delays possible if IRS issues CP566 (info request). | Week 2–11 – Watch mail for IRS letters; respond quickly if requested. |
8. Receive ITIN Notice If rejected (CP567), fix issues & reapply with corrections. | Week 7–11 – Keep letter safe for tax records. |
9. Renewal (if needed) Renew via W-7 before filing to avoid return delays. | Ongoing – Check ITIN status annually if filing US returns. |
Common Form W-7 rejection reasons from the IRS
What happens:
IRS rejects if there’s no attached U.S. tax return or qualifying exception; or the wrong box (a–h) is ticked for the situation.
How to avoid:
Attach the U.S. federal return unless you clearly qualify for an exception (e.g., bank interest, scholarship, mortgage reporting).
Match the Reason box to your fact pattern and include all exception proof if claiming one. See Instructions for Form W-7 and Pub 1915. IRS+1
What happens:
Copies aren’t accepted (e.g., not from the issuing agency), documents expired, or names don’t match the W-7.
How to avoid:
Use a valid passport (often sufficient alone). If sending copies, they must be certified by the issuing authority (not just notarised).
Ensure names, dates of birth, and addresses match exactly across W-7 and ID.
A CAA can authenticate most documents so you keep your passport. IRS+1Taxpayer Advocate Service
What happens:
IRS can’t tie the W-7 to a valid return; or the return is unsigned/invalid → “hard reject” in the ITIN-RTS.
How to avoid:
Attach a complete, signed federal return (e.g., Form 1040) with all W-2/1099 schedules.
Check that names/SSNs/addresses on the return match the W-7.
If IRS requests info (CP566), respond fully and on time to avoid final rejection. IRSTIGTA
What happens: Applicant doesn’t need an ITIN (e.g., eligible for SSN), or applies for a use case ITIN doesn’t cover.
How to avoid:
Confirm you’re not eligible for an SSN and that the stated tax purpose requires an ITIN (W-7 instructions spell this out).
If you receive CP567 (rejection), it often cites ineligibility or invalid documents—fix exactly what’s listed and reapply. IRS+1
What happens: Filing with an expired ITIN triggers processing delays and potential rejection until it’s renewed.
How to avoid:
Check if your ITIN expired (e.g., not used on a return in the last three years) and renew before filing, using W-7 (no return needed for some renewals). IRS
What happens:
IRS letters go astray; applicants miss a CP566 info request → application gets rejected.
How to avoid:
Use a stable, deliverable UK address, monitor mail, and reply promptly to any IRS request. Keep copies of everything you send. TIGTA
What happens:
Wrong box ticked, multiple boxes ticked without proof, missing signatures, or data entry mistakes.
How to avoid:
Review W-7 line-by-line; ensure one correct Reason and consistent data. A CAA review significantly reduces these errors. IRShelp.w7itin.com
Partnership Opportunities with our UK based Certified Acceptance Agents (CAA)
As IRS-authorised Certifying Acceptance Agents, we help UK accountants and advisors expand their service offerings through white-label or co-branded ITIN services. This partnership allows firms to deliver comprehensive tax solutions while we handle the specialised processing behind the scenes.
UK professionals benefit from new revenue streams and enhanced client loyalty without developing extensive cross-border tax expertise. Clients receive faster processing, retain their original documents, and enjoy local UK support throughout the application process. Our streamlined workflow involves client engagement through your firm, document gathering, completion and certification of the W-7 form, and direct delivery of processed ITINs.
We charge £399.95 per ITIN submission for your clients. We can charge you this amount freeing you up to charge more to your client for the additional work you perform.
