The one-page form everybody asks for and nobody explains

Figures relate to tax year 2025 (US)

Somebody will not pay you until you send a W9 form. Somebody else sent you a questionnaire that looks similar and is not.

Both are asking the same underlying question, which is whether you are American for tax purposes.

Answering it correctly costs nothing. Answering it wrongly, or ducking it, costs a surprising amount.

Key takeaways

• A W-9 certifies that you are a US person to whoever pays you.
• It goes to the payer, never to the IRS.
• A US citizen never signs a W-8BEN instead.
• Refusing triggers backup withholding at 24%.
• A British bank's FATCA questions are not the same form.
• You need a US tax number to complete it.
• Signing a false one is a serious matter.
• A British address on it is perfectly normal.

What is a W9 form?

A certification of your name, tax number and status as a United States person. According to IRS guidance on the form, you give it to whoever is paying you so they can report the payment correctly. It is a statement to them rather than a filing.

Our guide to online sellers and Form 1099-K covers what payers report.

Nothing about it reaches the IRS directly.

Who can ask for a W9 form?

Anybody who may have to report a payment to you, which covers American clients, banks, brokers, platforms and pension providers. Usually the request is routine. So the person asking is following their own rules rather than singling you out.

A British company paying a British supplier has no business asking.

Ask why if the request looks out of place.

Should you ever sign a W-8BEN instead?

No, and this is the single most important sentence here. That form certifies you are not American, so an American citizen signing it is making a false statement. Living in Britain does not change your status for this purpose.

Our guide to a FATCA letter from a UK bank covers bank questions.

The two forms are opposites, not alternatives.

Two forms, opposite answers

What if you refuse the W9 form?

Backup withholding, which means the payer holds back 24% of what they owe you and sends it to the IRS. But you get it back only by filing a return and claiming it. So refusing turns a one-page form into a year-long cash flow problem.

Our guide to estimated tax payments from the UK covers the cash flow.

The rate applies to the gross payment, not the profit.

Do you need a US tax number?

Yes, because the form has nowhere to put anything else. Usually a citizen uses their social security number. If you have none, you apply for a number first. There is no version of this form that works with a national insurance number.

Our guide to ITIN applications from the UK covers the alternative.

An American citizen should hold a social security number already.

Can you put a British address on a W9 form?

Absolutely, and it causes no problem at all. After all, the address is just where the payer sends any information return. Also, millions of Americans live abroad. Inventing an American address to look conventional is a bad idea for several reasons.

Our guide to the IRS online account from the UK covers address records.

Use the address you actually live at.

A worked example

Take an illustrative case. An American designer in Bristol invoices a New York agency for a project.

The agency asks for a W-9 before releasing payment, which is entirely standard.

She completes it with her social security number and her Bristol address.

Had she sent a W-8BEN instead, she would have certified something untrue to avoid a form she had no reason to fear.

Is a bank questionnaire a W9 form?

No, though it asks a similar question. British banks run their own self-certification under the information exchange rules, and their forms are not IRS documents. Some banks hand you a genuine W-9 as well, which is where the confusion starts.

Our guide to a UK bank account closure covers what banks do next.

Answer both honestly and consistently.

Does it make you taxable on anything?

Not at all, and this misconception stops people completing it. The form reports nothing and charges nothing; it simply tells a payer which reporting rules apply to them. Your tax position is identical whether or not you sign it.

Our guide to US filing thresholds for expats covers what actually creates a duty.

The form follows your status rather than creating it.

What does the payer do with a W9 form?

First they keep it on file. Then they use it to prepare an information return at the end of the year. The copy they send you is what you reconcile against your own records. They do not forward the form itself anywhere.

Our guide to a CP2000 notice from abroad covers mismatches.

A wrong number on the form causes a mismatch later.

What if your details change?

Send a fresh one, because the payer relies on what they hold until you say otherwise. A change of name, address or entity type all warrant an update. Platforms in particular carry on using stale information for years.

Update it the same week you move.

Keep a copy of every version you sent.

Does a company sign a W9 form?

An American company does, through an authorised person, using its employer number. A British company is not a United States person and signs the business version of the other form instead. The entity's nationality decides it, not yours.

Our guide to Form 5472 for UK owners covers American entities abroad.

Your own citizenship does not make your British company American.

What about a US LLC you own?

The LLC completes one in its own name, and the classification box is where people go wrong. A single member company is usually disregarded, which changes whose number goes on the form. Read the instructions on that line carefully.

Our guide to closing a US LLC from the UK covers the entity.

The wrong classification produces a reporting mismatch.

Can you be asked for one by a UK employer?

Only if they make payments reportable to the IRS, which is unusual. A purely British employer paying British payroll has no reporting duty to America and no reason to ask. Where an American parent company is involved, the picture changes.

Our guide to shadow payroll arrangements covers cross-border employers.

Ask what reporting they think applies.

Is it safe to email a W9 form?

It carries your full tax number, so treat it like a passport scan. So use a secure portal where one exists. If there is none, ask for one. Plenty of identity theft starts with a form like this sitting in an inbox.

Our guide to the identity protection PIN covers the aftermath.

Never send one to an unsolicited request.

How do you spot a fake W9 form request?

Look at who is asking and whether they have any reason to pay you. The IRS never requests one, so an email claiming to be from them is a scam by definition. A real request comes from a client, a bank or a platform you deal with.

Our guide to IRS letters after streamlined covers genuine correspondence.

In our practice these scams spike every filing season.

What if you signed the wrong form before?

Correct it, and the sooner the better. Still, do not panic about it. Send the right form to the payer with a short note, and look at whether the years behind it were reported properly. A false certification left standing is worse than one corrected voluntarily.

Our guide to streamlined eligibility covers coming forward.

Fix the form and the returns together.

Does signing one trigger FATCA reporting?

At a bank it confirms that your account gets reported, which would have happened anyway once they identified you. The form documents the conclusion rather than causing it. Refusing simply makes the bank treat you as reportable regardless.

Our guide to Form 8938 reporting covers your own filing.

Banks report on indicia, not on your cooperation.

What W9 form records should you keep?

A copy of every form you sent, who you sent it to and when, and the information returns you receive back. Those three let you reconcile what was reported about you against what you reported yourself.

Our guide to a tax transcript request covers checking the IRS record.

Keep them for at least four years.

Does a W9 form expire?

Not on a date, unlike its foreign counterpart. A payer keeps using the one they hold until something changes. So in practice it lasts until you move, change your name or change your entity type, and then you send a fresh one.

Some platforms ask again every few years anyway.

That is their policy rather than a rule.

What if a payer still withholds?

Chase it at once, because the money has usually not gone yet. Often a form sits unprocessed in somebody's inbox while payments run on the old setting. If it has gone, you claim it back on your return as tax already paid.

Our guide to Form 843 refund claims covers recovery.

Ask for written confirmation that the form is on file.

Do dividends and interest need one?

Yes, if the payer is American. A brokerage in New York holding your shares wants one before it pays anything, and so does a bank you kept open there. Otherwise the same withholding applies to investment income as to fees.

Our guide to US withholding tax for UK investors covers the rates.

Brokers are stricter about this than most clients.

What about a joint account?

The payer usually wants one from the first named holder, though both may be asked. Where one holder is American and the other is not, the account gets treated as reportable anyway. So a mixed couple should expect questions from both sides.

Our guide to joint accounts for US-UK couples covers shared holdings.

Keep the paperwork consistent between you.

Does a trust or estate sign one?

An American trust or estate does, through its trustee or executor, using the entity number rather than a personal one. A British trust is not a United States person, so it signs the business version of the foreign form instead.

Our guide to Form 56 and fiduciary notices covers acting for an estate.

Never put your own number on an entity form.

Is there a deadline to return it?

No statutory one, though payers set their own. Most hold payment until the form arrives, which is the real deadline. If a year end is approaching, get it in before the payer prepares its information returns.

January is the busy month for those returns.

Late forms produce corrected ones, which nobody enjoys.

Does a W9 form affect your UK tax?

Not directly, because HMRC takes no interest in it. But the income behind it is British taxable if you are resident here, whatever the American payer reports. So the form is one side of a picture your Self Assessment has to complete.

Our guide to registering for Self Assessment covers the British return.

Report the income here even though the form went there.

What goes in the exemption boxes?

For almost every individual, nothing at all. Those boxes exist for entities that are exempt from backup withholding or from the information exchange rules, and a person filling one in by mistake creates a problem. So leave them blank unless you know why you would not.

Banks sometimes query a blank box out of habit.

Blank is still the right answer for an individual.

Can somebody sign it for you?

Only with proper authority, and most payers will not accept it. The signature certifies your own status under penalty of perjury, so an accountant cannot simply sign on your behalf. If you are abroad and cannot sign, a scanned signature is usually accepted.

Our guide to IRS power of attorney covers acting for somebody.

Even an agent with authority rarely signs this one.

Does a sole trader use their own name?

Yes, with the trading name underneath if there is one. The tax number is still your personal one, because a sole trade is not a separate person. People running a business under another name often put the business first and cause a mismatch.

Our guide to UK contractors with US clients covers freelance work.

Your legal name goes on the first line, always.

What if the payer loses it?

Send another one, and do not take it personally. Large platforms lose forms routinely, and withholding often starts before anybody notices. Keeping your own dated copy is what turns a two-week argument into a two-minute one.

Resend it through the same secure channel.

Ask them to confirm receipt in writing.

How to complete a W9 form

1. Check the request comes from somebody who may pay you.
2. Confirm you are a US person, which citizenship settles.
3. Use your social security number or ITIN, never a foreign one.
4. Give your real British address rather than an American one.
5. Tick the classification that matches the entity signing.
6. Never substitute a W-8BEN because you live abroad.
7. Send it through a secure channel, not plain email.
8. Keep a copy and refresh it when your details change.

Mistakes and penalties we see with a W9 form

The first is signing a W-8BEN because a British address felt like the foreign answer, which certifies something untrue.

The second is refusing to complete anything and losing 24% of every payment to backup withholding.

The third is giving a national insurance number in the tax number box, which no system will accept.

The fourth is emailing a completed one to an address nobody verified.

How US UK Tax Accountants helps

We settle the status question first, because every form in this area is just a different way of asking it and the answer rarely changes.

Then we make sure what payers report matches what you file. Our US federal returns service covers the return.

If a client or a bank has asked for something you do not recognise, get in touch.

Last reviewed 28 October 2026. This article is general information and not personal tax advice, and forms change.