Does your British spouse need a US tax number?

An ITIN is an Individual Taxpayer Identification Number, issued by the IRS to people who need a US tax number but are not eligible for a Social Security number. It exists for tax administration only. It confers no immigration status and no right to work.

No, and this is the most useful thing to know before starting an application. Many Americans married to non-US spouses file separately and claim nothing in respect of the spouse, in which case the return does not need a number for them.

So the usual practice in that case is to write NRA in the space rather than leaving it blank.

That reflects a spouse who is a non-resident alien with no American filing position.

So the first question is not how to apply, but whether anything on your return actually requires the number.

In our practice most clients in this position never need one at all, and finding that out early saves a great deal of effort.

When the return does something with the spouse rather than merely naming them. The common cases are an election to file jointly, a credit or benefit claimed in respect of the spouse, or the spouse having their own American filing obligation.

First, a joint election is the big one, because it brings the spouse's worldwide income into the American system.

Couples usually decline that, which is why most never need the number.

Where the spouse owns US-situated assets or receives US-source income, they may need one for their own return instead.

Form W-7 is the application. The IRS publishes the form and its instructions, which set out who may apply, what identity evidence is acceptable, and which reason for applying to tick.

However, the reason code matters more than people expect.

It determines what supporting evidence the application needs.

Choosing the wrong one is a common cause of rejection and of months lost.

Normally the opposite. The application usually travels attached to the tax return that creates the need for the number, rather than being submitted separately in advance. So the sequence runs opposite to what most people assume, and assuming wrongly costs a filing season.

That ordering catches people who assume they must get the number first.

The IRS explains the process on its ITIN pages.

There are exceptions, and the instructions set out which categories may apply without a return attached.

Documentary evidence of identity and foreign status, and the rules are strict. A passport is the single document that can satisfy both, which is why it is the usual choice for a British spouse.

Originals or certified copies from the issuing agency are what the process contemplates, and the IRS sets out how to apply and what documents it accepts.

That prospect is what stops most people, understandably.

There are routes that avoid posting a passport, which the next section covers.

Not necessarily. The IRS operates an acceptance agent programme, and certain agents can verify original documents so they do not have to travel. Some IRS offices also offer document review by appointment.

For a British spouse that difference is substantial.

Posting a passport abroad for an uncertain period is impractical for anybody who travels.

So it is worth establishing which route is available to you before starting the form.

Longer than a domestic process, and the timing varies with the season and the completeness of the application. The practical point is that it is measured in weeks and months rather than days.

That matters when a return deadline is approaching.

However, a rejected application restarts the clock rather than pausing it.

So accuracy at the first attempt is worth more than speed, and the common rejections are documentary rather than substantive.

It can lapse through disuse. A number that has not appeared on a return for several consecutive years stops being usable, and a return filed with a lapsed number gets treated as though the number were missing.

In practice that catches households whose circumstances changed.

A couple who elected jointly for a few years and later filed separately may have a number quietly going stale.

If the number is needed again later, renewal rather than a fresh application is the route.

No. The number is an administrative identifier, not a status. Holding one does not make your spouse a US taxpayer, does not create a filing requirement, and does not bring their income into the American system.

That reassurance matters, because the fear is common and reasonable.

What brings a spouse into the system is the joint election, not the number.

The number simply lets the IRS match a person to a filing that already exists.

Rarely, and the trade is a poor one. Electing to file jointly brings your spouse's worldwide income permanently into the American system, which is a far larger commitment than an administrative form.

For a British spouse with British income and British pensions, that usually means more reporting and sometimes more tax.

The election can also be awkward to unwind.

Our guide to married filing separately with a UK spouse sets out the comparison properly.

A child born abroad to a US-citizen parent may well be a US citizen, in which case the route is a Social Security number rather than an ITIN. The two are not interchangeable.

So establishing the child's citizenship comes first.

Our guide to children born abroad to US citizens covers how that works, and the Social Security Administration explains applying from abroad.

Only where a child is genuinely not a US person does the ITIN question arise at all.

A sequence that avoids the common rejections.

An ITIN is a nine-digit number formatted like a Social Security number, and it always begins with a nine. It goes in the same box on the return that a Social Security number would occupy.

Banks and brokers sometimes ask for one on American paperwork.

That request is about information reporting rather than about tax residence.

Supplying an ITIN in that context does not change anybody's status, and refusing to supply one can mean withholding at a higher rate.

Only in defined circumstances. The ordinary route attaches the application to a return, and the exceptions cover specific situations such as certain withholding and reporting cases rather than general convenience.

The instructions list those categories.

Picking an exception that does not actually fit is a common cause of rejection.

So where no return is involved, read the exception carefully before relying on it.

The number gives way. Where somebody becomes eligible for a Social Security number, that becomes their identifier and the ITIN stops being the right one to use. That happens more often than people expect, usually through a change of status rather than a move.

The two should not be used side by side.

Telling the IRS lets them link the records, so earlier filings stay connected to the right person.

That matters most where a refund or a credit depends on history under the old number.

The IRS charges nothing for the application itself. Costs arise around it instead, from certified copies of documents, from an acceptance agent where you use one, and from the preparation time if an adviser handles it.

So the number is free and the process is not.

Those costs are worth weighing against whether the ITIN is genuinely needed.

For many separate filers it is not, which makes the cheapest route establishing that first.

Not really, and that is worth saying plainly. First, it confers no immigration status whatsoever. Second, it gives no right to work in the United States. Third, it does not affect visa applications or residence in any way at all.

However, it does appear on American financial paperwork.

For instance, a bank or broker may ask for one when opening an account or reporting income.

So the number solves an administrative problem and nothing beyond it. In short, treat it as a filing identifier rather than as a status.

First, read the reason given, because most rejections are documentary rather than substantive. Then correct the specific defect rather than starting the whole application again. In practice that is the common outcome, and it is recoverable without starting again from nothing.

However, a rejection does not pause any filing deadline.

So the return it was attached to may need handling separately in the meantime.

For example, an agreed extension can buy the time to resubmit. In short, treat the rejection as a document problem and the deadline as a separate one.

Consider an American in Leeds married to a British spouse with purely British income. For years she filed separately, entered NRA in the space, and needed nothing further.

Then the couple bought a property together and the reporting changed. The question of whether a number was needed arose for the first time in a decade.

Establishing that before filing season, rather than during it, meant the application went in without a deadline pressing on it.

This example is illustrative. The pattern it shows is the useful one: the need arrives with a change of circumstances rather than with the marriage.

The first applies when nothing on the return requires it. That is months of effort for no purpose.

The second picks the wrong reason for applying, which is the most frequent documentary rejection.

The third assumes the number must be obtained before the return. It usually travels with it.

The fourth makes the joint election to dodge the paperwork, which trades an administrative form for a permanent expansion of the American tax net.

We start with whether you need one, because for many clients the honest answer is no and that saves everybody months.

Where one is needed we prepare the application alongside the return it belongs to, so the two arrive together and in order.

Our US federal returns service covers the filing, and fees stay fixed and agreed in writing beforehand. How we work sets out the process.

If a form has asked for a number your spouse does not have, talk to us before applying for one.