Does my British spouse need an ITIN if I file married filing separately?

No. On a married filing separately return you enter your spouse's name on the filing status line, and where they do not have and are not required to have an SSN or ITIN, the Form 1040 instructions direct you to enter NRA in the identifying number space. No Form W-7 is filed. Since 2018 the IRS will not issue an ITIN to a spouse who is not claimed for an allowable tax benefit, so applying anyway invites a rejection.

Which box do I tick on Form W-7 for a non-US spouse?

Box e, spouse of a US citizen or resident alien. You must also enter the US spouse's full name and Social Security number alongside it, and include a marriage certificate as evidence of the relationship. Box h, the other category, is for situations where no US tax return is being filed and a documented exception applies. A streamlined submission contains original delinquent returns, so box e is correct.

Will the IRS accept a UK solicitor's certified copy of a passport?

No. GOV.UK certification, where a solicitor, notary, bank official or chartered accountant writes that the copy is a true copy of the original seen by them, is a notarised copy in IRS terms, and the IRS does not accept notarised copies for ITIN applications. The IRS accepts an original document or a copy certified by the issuing agency with its official stamped seal. For a UK passport that means HM Passport Office, which does not routinely provide this.

How long will the IRS keep my spouse's original passport?

The IRS states that supporting documents are returned to the mailing address on line 2 of Form W-7 within 60 days, and publishes overall Form W-7 processing as 7 weeks, extending to 9 to 11 weeks for applications submitted from overseas or during the 15 January to 30 April peak. Add international post at both ends. If documents are not returned, the IRS gives 800-908-9982 in the US and 267-941-1000 from abroad.

Are there IRS Taxpayer Assistance Centres in the UK?

No. The IRS list of Taxpayer Assistance Centres offering ITIN services covers locations in the United States and Puerto Rico only, and appointments are booked on 844-545-5640 with the IRS warning that it may take several weeks. From the UK, the in-person equivalent is a Certifying Acceptance Agent, and the IRS publishes a United Kingdom list of acceptance agents. A TAC is only realistic if your spouse is already travelling to the United States.

Can I send the Form W-7 separately to speed up my streamlined filing?

No, and it usually causes the opposite. The IRS instruction is to submit the ITIN application along with the returns, information returns and other documents filed under the streamlined procedures, so the whole package goes to the Streamlined Foreign Offshore unit in Austin rather than to the ITIN Operation post office box. Splitting it leaves the W-7 without the return it must be validated against, and the streamlined returns without a number.

Form W-7: ITIN for a Non-US Spouse in Streamlined Filing

An IRS Streamlined Filing cannot be processed without a valid taxpayer identification number for every person named on the returns, and where a US citizen living in the United Kingdom wants to file jointly with a British spouse who has never had any US connection, that number has to be an ITIN applied for on Form W-7. The IRS sets the rule out on its Streamlined Filing Compliance Procedures page at https://www.irs.gov/individuals/international-taxpayers/streamlined-filing-compliance-procedures: all returns submitted under the streamlined procedures must have a valid taxpayer identification number, a US citizen or resident alien must use a Social Security number, and a taxpayer who is ineligible for an SSN and does not have an ITIN may still make a streamlined submission if it is accompanied by a complete ITIN application. That final clause is the entire workaround, and it is also where the risk sits.

The risk is sequencing. A Streamlined Foreign Offshore submission is a paper submission, mailed as one package to a single unit in Austin, Texas. The Form W-7 travels inside that package. If the W-7 is rejected, and rejections are usually documentary rather than substantive, the returns attached to it are caught up in the same correspondence. In the packages we prepare, the ITIN application is the single most common reason a streamlined case that was otherwise ready to go sits unprocessed for months. The second thing worth saying at the outset, because almost nobody says it, is that in a large proportion of these cases the non-US spouse should not be on the return at all, and the ITIN question disappears entirely.

Does an IRS Streamlined Filing require an ITIN for a non-US spouse?

Only if the non-US spouse is actually named on the returns in a way that requires a number. Streamlined Foreign Offshore, described by the IRS at https://www.irs.gov/individuals/international-taxpayers/u-s-taxpayers-residing-outside-the-united-states, requires three years of delinquent or amended returns, six years of FBARs filed electronically through the FinCEN BSA E-Filing System at https://bsaefiling.fincen.treas.gov, payment of tax and interest, and a signed Form 14653 certifying non-willful conduct. The taxpayer identification number requirement attaches to the returns. The FBARs are a separate matter: a spouse who is not a US person has no FBAR obligation of their own and needs no ITIN for FBAR purposes.

So the ITIN question is really a filing status question dressed up as an administrative one. If the US citizen files a joint return with the non-US spouse, the spouse becomes a named filer, signs the return, and needs an ITIN. If the US citizen files married filing separately, the spouse is named on the filing status line but is not a filer, and the IRS instructions for Form 1040 at https://www.irs.gov/instructions/i1040gi direct the filer to enter the spouse's name and, where the spouse does not have and is not required to have an SSN or ITIN, to enter NRA in the identifying number space. No W-7, no passport, no delay.

There is a further point that catches people out. Since the 2018 tax year, a spouse cannot obtain an ITIN merely to be listed on a return. IRS Topic 857 at https://www.irs.gov/taxtopics/tc857 confirms that spouses and dependants now qualify only where they are claimed for an allowable tax benefit. A W-7 submitted for a non-US spouse on a married filing separately return, with no benefit claimed, will be rejected. That is the correct outcome, not an error, and it is why the NRA entry exists.

Who needs an ITIN, and who must use an SSN?

An ITIN is a nine-digit number the IRS issues to a person who has a federal tax purpose but is not eligible for a Social Security number. The IRS ITIN page at https://www.irs.gov/tin/itin/individual-taxpayer-identification-number-itin is explicit about what it is not: it does not confer work authorisation, it does not change immigration status, it does not create entitlement to Social Security benefits or the earned income credit, and it has no function as identification outside the federal tax system. A British spouse who obtains an ITIN has not become an American taxpayer by doing so. They have obtained a filing reference.

Eligibility for an SSN, not nationality, is the dividing line. In practice, in the UK households we deal with, the split runs as follows:

The US citizen or green card holder making the streamlined submission must use an SSN. If they have never had one, the position is different and more complicated than an ITIN application, because an ITIN is not available to a person who is eligible for an SSN.
A British spouse with no US status, no green card and no US work authorisation is not eligible for an SSN and therefore uses an ITIN if a number is required.
A dual US-UK national spouse is eligible for an SSN and must obtain one. An ITIN application for that person will be rejected, and the streamlined package will stall behind it.
Children born in the UK to a US citizen parent are usually US citizens themselves and are SSN cases, not ITIN cases, even where they have never set foot in the United States.
A UK-born child who is not a US citizen and is claimed for an allowable tax benefit is an ITIN case, and is subject to a stricter documentary standard than a spouse.

We would put the dual national point first among the errors we correct. Families who have lived in the UK for twenty years frequently have a spouse who acquired US citizenship through a parent and has never registered it. Filing a W-7 for that person is not a shortcut. It is a rejection, and it usually costs a full processing cycle.

Which Form W-7 reason code applies to a spouse?

Form W-7, described at https://www.irs.gov/forms-pubs/about-form-w-7, opens with a set of lettered boxes headed reason you are submitting Form W-7. Exactly one applies to a non-US spouse of a US citizen or resident alien. The instructions at https://www.irs.gov/instructions/iw7 run through them:

Box a - nonresident alien claiming a reduced rate of withholding under a tax treaty, without filing a return.
Box b - nonresident alien filing a US federal tax return, which requires a complete foreign address.
Box c - US resident alien filing a return on the basis of the substantial presence test.
Box d - dependant of a US citizen or resident alien, requiring the relationship and the sponsoring person's full name and SSN or ITIN.
Box e - spouse of a US citizen or resident alien. This is the box for a British spouse joining a joint return, and it requires the US spouse's full name and SSN to be entered alongside it.
Box f - nonresident alien student, professor or researcher filing a return or claiming an exception.
Box g - dependant or spouse of a nonresident alien holding a US visa.
Box h - other, used where a documented exception to the return-attachment rule applies.

Box e is the correct code, and the supporting evidence of the relationship is a marriage certificate. Practitioners occasionally reach for box h on the theory that a streamlined submission is unusual enough to be an exception. It is not. A streamlined package contains original delinquent returns, so the ordinary rule applies: the W-7 is submitted with a return, and box e is the reason. The exceptions in box h exist for situations where no return is being filed at all, such as a bank or withholding agent requiring a number for reporting purposes.

Getting the code wrong matters more than it looks. The ITIN Operation processes the W-7 against the attached return and checks that the claimed reason is consistent with what the return actually does. A box e application attached to a set of returns filed married filing separately, with no allowable benefit claimed for the spouse, fails that consistency check.

What documents does the IRS accept, and why is a UK certified copy usually the wrong one?

This is where UK applicants come unstuck, and the reason is a genuine mismatch between two national systems. The IRS accepts thirteen categories of document to establish identity and foreign status, listed in the W-7 instructions. A valid unexpired passport is the only one that stands alone for an adult applicant. Everything else has to be paired. For a British spouse, in reality, the application is a passport application: the passport does the whole job, and the alternatives, such as a national identity card or a foreign voter registration card, are of little use to someone holding a UK passport.

The IRS will accept an original document, or a copy certified by the agency that issued it. The ITIN documentation FAQs at https://www.irs.gov/individuals/international-taxpayers/itin-documentation-frequently-asked-questions-faqs define a certified copy as one that the original issuing agency provides and certifies as an exact copy of the original, bearing an official stamped seal from that agency. Notarised copies are not accepted. There is a narrow exception for dependants and spouses of US military personnel stationed overseas, which does not help a civilian family in London.

Now put that against the UK system. GOV.UK explains at https://www.gov.uk/certifying-a-document that certifying a document in the United Kingdom means asking a professional of good standing - a solicitor, a notary, a bank official, a chartered accountant - to write that the copy is a true copy of the original seen by them, then sign, date and give their details. That is a perfectly good certification for a UK bank, a UK landlord or the Land Registry. It is a notarised or professionally witnessed copy in IRS terms, and the ITIN Operation will not accept it. The issuing agency for a UK passport is HM Passport Office, and HM Passport Office does not, as a matter of routine service, issue certified photocopies of passports to the passport holder. So the option the IRS points to first is, for most UK applicants, simply not available.

The IRS also names US embassy and consulate officers as an alternative certifying route, while cautioning that services vary between countries. Running in the other direction, GOV.UK guidance at https://www.gov.uk/guidance/documents-for-british-people-abroad shows how restricted consular certification has become: in non-Commonwealth countries British embassies will certify a copy of a UK passport only where a local notary cannot do it or the requesting body insists on it, and in Commonwealth countries British posts will not certify documents at all. Do not build a submission timetable around a consular appointment you have not already secured.

Should you post an original UK passport to Texas?

This is the question clients actually ask, and it deserves a straight answer rather than a shrug. The IRS position, on its how to apply page at https://www.irs.gov/tin/itin/how-to-apply-for-an-itin, is that supporting documents will be returned to the mailing address on line 2 of the Form W-7 within 60 days. The ITIN documentation FAQs give the numbers to call if they are not: 800-908-9982 within the United States, and 267-941-1000 for callers from abroad. Overall Form W-7 processing is published as 7 weeks, extending to 9 to 11 weeks for applications filed during the peak season of 15 January to 30 April or submitted from overseas.

The mechanical risk is small. The practical cost is not. A British spouse who posts their passport to Austin is without it for a period the IRS measures in weeks and which, once international post is added at both ends, is realistically longer. That is a passport unavailable for a work trip, a family funeral, a house purchase requiring identity verification, or a UK visa or settlement application for a relative. In a household that is already filing three years of delinquent returns under a certification of non-willfulness, an unplanned two-month absence of a passport is a real disruption to a person who has done nothing wrong and is only on the paperwork because they are married to a US citizen.

It also creates a second problem specific to streamlined. If the passport has to be posted, and the passport is also needed for something else, the temptation is to hold the streamlined package until the passport is free. Streamlined submissions are made under a certification that the failure to file was non-willful, and delay for administrative convenience does nothing for that story. The submission should go when it is ready. That argues strongly for a route that does not involve posting the original.

What does a Certifying Acceptance Agent in the UK actually do?

The IRS authorises two kinds of agent, and the difference is the whole point. Its acceptance agents page at https://www.irs.gov/tin/itin/itin-acceptance-agents distinguishes an Acceptance Agent, which reviews and mails supporting documents, from a Certifying Acceptance Agent, which authenticates supporting documents and returns the authenticated documents immediately. A CAA looks at the original passport in front of them, certifies it to the IRS on its own authority, hands the passport straight back, and sends the certification with the W-7. The passport never crosses the Atlantic.

The IRS publishes a country list, and the United Kingdom list sits at https://www.irs.gov/individuals/international-taxpayers/acceptance-agents-united-kingdom. It is a substantial list, with agents across London and the larger UK cities. Two limits are worth knowing before you rely on the route:

A CAA can authenticate supporting documents with two exclusions: foreign military identity cards, and any document for a dependant that is not a passport or a birth certificate. For a spouse applying on box e with a UK passport, neither exclusion bites.
Where a dependant child is involved and the evidence is a school record, a medical record or a utility statement, the CAA cannot authenticate it. That material has to be mailed to the IRS with the package regardless.
The country list identifies agents but does not label which entries hold full certifying authority, so confirm the CAA designation directly with the agent before booking.
CAA services are chargeable. That is a private commercial arrangement, not an IRS fee, and it is the price of keeping the passport in the UK.

For a UK household assembling a streamlined package, the CAA route is usually the correct one. It removes the documentary failure mode that causes most rejections, it removes the passport absence, and it removes a fortnight of international post from the front of the timetable.

Can you use an IRS Taxpayer Assistance Centre from the UK?

Not in the UK, no. A Taxpayer Assistance Centre with ITIN services is an excellent option, because staff can authenticate documents in person and return them at the end of the appointment. The IRS list at https://www.irs.gov/tin/itin/irs-taxpayer-assistance-centers-with-itin-services covers only locations in the United States and Puerto Rico. There is no equivalent walk-in facility in the United Kingdom. Appointments are made on 844-545-5640 and the IRS itself warns that it may take several weeks to get one, and TAC staff can authenticate all documents for an in-person applicant except school and medical records for dependants.

The practical relevance for a UK family is narrow but real. If the non-US spouse is travelling to the United States anyway, a TAC appointment booked well in advance around that trip is a free alternative to a CAA fee. It requires the trip to fall at the right moment relative to the streamlined package, which in our experience it rarely does. Treat it as an opportunistic saving, not a plan.

How does the W-7 travel with a paper streamlined package?

This is the part that is genuinely under-explained elsewhere, and it is where careful assembly earns its keep. A standalone ITIN application goes to the IRS ITIN Operation at P.O. Box 149342, Austin, TX 78714-9342. A Streamlined Foreign Offshore submission goes to the Internal Revenue Service, 3651 South I-H 35, Stop 6063 AUSC, Attn: Streamlined Foreign Offshore, Austin, TX 78741, and the IRS states that these procedures are for paper submissions only. Both are in Austin, and they are not the same destination.

The streamlined instruction is that the ITIN application is submitted along with the required tax returns, information returns and other documents filed under the streamlined procedures. In other words, the package stays whole and goes to the streamlined address. Splitting it - sending the W-7 separately in the hope of getting the number first - breaks the link the IRS relies on to validate the ITIN application against a return, and leaves a streamlined package with an empty number field. Both halves then need correspondence.

Three assembly points follow from the way the ITIN Operation handles these:

The identifying number field for the ITIN applicant is left blank on the returns. The IRS instruction is to leave the SSN area blank on the return accompanying a Form W-7; writing applied for, a National Insurance number or a UK Unique Taxpayer Reference in that box is a rejection trigger.
The US spouse's SSN goes on the return and is also entered on the W-7 itself as the identifying information for the box e relationship.
The Form 14653 certification and the original signed returns still have to be complete and signed by both spouses where the returns are joint. The ITIN application does not excuse anything else in the package.

The single biggest scheduling implication is this: the ITIN Operation processes the number first and the returns move on afterwards. Every week the W-7 spends in correspondence is a week the streamlined returns have not started processing. A W-7 that is documentarily perfect on first submission is worth more to the timetable than anything else you can control.

Should the non-US spouse be on the return at all?

Very often, no. A joint return with a nonresident alien spouse is not automatic. It requires an election under section 6013(g) to treat the nonresident spouse as a US resident, and the IRS sets out the conditions at https://www.irs.gov/individuals/international-taxpayers/nonresident-spouse. The election is made by attaching a signed statement to the joint return giving the name, address and identification number of each spouse, which is precisely why the ITIN is needed. The consequences are substantial and permanent in character:

Both spouses must report their entire worldwide income for the year of the choice and for all later years, unless the choice is ended or suspended. A British spouse's UK salary, UK investment income, UK rental profits and UK company income all come inside the US return.
Treaty benefits that would otherwise be available to the non-US spouse as a UK resident are generally not available once the election is in place.
The election ends on revocation by either spouse, death, legal separation or inadequate records, and once ended it is a once-in-a-lifetime matter: neither spouse can make the choice again with each other or with anyone else in any later tax year.
The non-US spouse signs the return and is jointly and severally liable for the tax shown on it.

Read that list against what a streamlined submission is for. The purpose is to bring a delinquent US citizen into compliance for three years with a non-willfulness certification. Spending a once-in-a-lifetime election, pulling a British spouse's entire financial life into the US system permanently, and adding an ITIN dependency to a paper package, in order to gain a joint filing benefit that in a UK household is frequently eliminated by the foreign earned income exclusion or foreign tax credits anyway, is a poor exchange. In most of the UK streamlined cases we prepare, married filing separately with NRA in the spouse's identifying number field is the right answer, and no Form W-7 is filed.

The cases where the ITIN is genuinely worth having tend to share features: a US citizen with meaningful US-source or unexcludable income where the joint rate bands and standard deduction actually change the number; a couple who will keep filing jointly for many years so the election is not a one-off; or a household where a non-US dependant is being claimed for an allowable benefit and a W-7 is going in regardless. Run the numbers both ways before you commit, because the decision is effectively irreversible.

A worked scenario: the London household that split the package

The following is an illustration, not a client file, and the figures are assumed. Take a US citizen who has lived in London for eleven years, works in banking, and has never filed a US return or an FBAR. She is married to a British architect with no US status. Together they hold a joint current account and a joint offshore savings account, and she holds a UK stocks and shares ISA and a workplace pension. She qualifies on the non-residency test for Streamlined Foreign Offshore, and the package is three years of Forms 1040, the associated information returns, six years of FBARs and a Form 14653.

The first draft was prepared as married filing jointly, on the assumption that joint was better. That required a section 6013(g) election, which required an ITIN for the husband, which required a Form W-7 on box e with his UK passport. He had a work trip to Singapore inside the window and would not release the passport, and the only certified copy he could obtain was a solicitor's certification, which the IRS does not accept. The package sat on a desk for eleven weeks waiting for a passport.

Reworked as married filing separately, the position changed completely. Her UK salary was covered by the foreign earned income exclusion and foreign tax credits, the residual US liability across the three years was small, the husband's income never entered the US system, and no once-in-a-lifetime election was spent. His identifying number field read NRA. There was no Form W-7 in the package at all, and the submission was mailed to Austin the following week. Had the joint numbers been materially better, the correct answer would have been to book a UK Certifying Acceptance Agent appointment for a morning between his trips, not to post the passport.

When does an ITIN expire, and how do you renew it?

An ITIN is not permanent. Any ITIN that is not used on a federal income tax return at least once in three consecutive tax years, whether as the number of a person filing the return or of a dependant included on it, expires on 31 December of that third consecutive year of non-use. ITINs issued before 2013 that were never renewed are also expired. Renewal is done on the same Form W-7, with the renewal reason indicated and supporting documentation to the same standard as an original application.

This has a direct bearing on streamlined work in two ways. First, a couple who obtained an ITIN years ago for a one-off purpose, then drifted out of the US system for the very reason that brought them to a streamlined filing, will frequently find that the old number has lapsed. Filing three years of delinquent returns bearing an expired ITIN produces delay and can cause claimed benefits to be disallowed. Check the number's status before the package is built, and renew rather than reapply. Second, a couple who make the section 6013(g) election and then let the joint filing lapse will find the spouse's ITIN expiring on the three-year cycle, which is one more piece of ongoing administration the election quietly buys.

The sequencing checklist we work to

The order below is the one that keeps a UK streamlined package moving, and each step exists because skipping it has cost somebody a processing cycle.

Confirm SSN eligibility for every person named on the returns before drafting anything, including checking whether a spouse or child is a dual national who must obtain an SSN rather than an ITIN.
Model the returns both jointly and separately, and treat the section 6013(g) election as a permanent decision rather than a filing convenience.
If separate filing wins, stop. Enter NRA and file no Form W-7.
If joint filing wins, check whether an existing ITIN exists and whether it has lapsed under the three-year non-use rule, and renew rather than reapply.
Book a UK Certifying Acceptance Agent before the returns are finalised, so the certification and the returns are ready at the same moment.
Assemble one package: Form W-7 on box e with the marriage certificate and the CAA certification, the three years of signed returns with the applicant's identifying number field blank, the information returns and the signed Form 14653.
File the six years of FBARs electronically through the FinCEN BSA E-Filing System, separately from the paper package.
Mail the paper package to the streamlined unit in Austin, not to the ITIN Operation post office box, and keep proof of posting.

The failure mode we see most often is not a wrong figure on a return. It is a British passport that could not be certified, in a package that could not move without it, for a joint election that the household did not need. Decide the filing status first, and the ITIN question usually answers itself.