The one deadline nobody can extend for you

Figures relate to tax year 2025 (US)

A thick envelope arrives and the heading says notice of deficiency. Somewhere inside is a date.

That date is the only one in the whole system that nobody can move. Not the IRS, not an adviser, not the court itself.

From Britain it matters twice over, because the post eats a fortnight of it before you have read a word.

Key takeaways

• A notice of deficiency is your ticket to the Tax Court.
• An address outside America gives you 150 days, not 90.
• The deadline is jurisdictional and cannot be extended for any reason.
• You do not have to pay the tax before petitioning.
• Small cases under $50,000 a year follow a simpler route.
• Most petitions settle with appeals rather than going to trial.
• The court sits only in America, though hearings can be remote.
• It will not hear FBAR penalties, which belong elsewhere.

What is the US Tax Court?

A federal court that hears income tax disputes before you pay the tax. That last part is what makes it unusual, and valuable. According to IRS guidance on appeal rights, every other route requires you to pay first and sue for the money back afterwards.

It is a national court based in Washington, with judges who travel to sit.

Nearly all its work turns on agreed facts rather than on a trial.

When can you go to the Tax Court?

Only after the IRS issues a statutory notice of deficiency, which practitioners therefore call the ticket. Correspondence, a proposed adjustment or a thirty day letter will not do. The notice is a formal determination, and it opens the door at the same moment it starts the clock.

Our guide to an IRS audit from abroad covers what comes first.

Without that notice, there is nothing for the court to review.

How long do you have to reach the Tax Court?

A hundred and fifty days, because the notice went to an address outside the United States. Somebody living in America gets ninety. That extra sixty days exists precisely because international post is slow, and it is the single most useful fact in this article.

Count from the date on the notice, not the day it reached you.

The longer period applies to the address, not to your nationality.

Can the Tax Court deadline be extended?

No, and this is the point people refuse to believe. The period is jurisdictional, meaning the court has no power to hear a late petition however good the reason. Illness, a postal strike, an adviser's error and a lost envelope have all failed.

Our guide to the statute of limitations covers the other time limits.

Treat the date as absolute and work backwards from it.

What if you miss the Tax Court deadline?

The IRS assesses the tax and collection begins, and your argument has to move to a different and worse forum. You can pay the liability, claim a refund and then sue, which is slower and requires the money up front. The merits may be identical and the position is far weaker.

Our guide to Form 843 refund claims covers the paying route.

Paying first is a real obstacle on a six-figure assessment.

Two ways to dispute, one deadline apart

Do you pay before the Tax Court hears you?

No, and that is the whole reason this court exists. You file, the assessment waits, and collection cannot begin while the case runs. For somebody abroad facing a disputed figure built on records the IRS never saw, that breathing space is the difference between arguing and capitulating.

Our guide to an IRS payment plan from abroad covers what happens if you lose.

Interest still runs on anything eventually found due.

What is a small tax case?

A simplified track for smaller disputes, elected when you file. In 2025 the limit stayed at $50,000 of tax and penalties in dispute for each year, counted year by year rather than in total. The procedure is looser, the hearing is less formal, and you can represent yourself more comfortably.

The trade is that nobody can appeal a small case decision.

For most expat disputes that trade is worth taking.

What does a Tax Court petition cost?

Sixty dollars, which surprises people who expect a court to be expensive. The cost of a case is professional time rather than fees, and a straightforward matter that settles with appeals costs far less than a trial. Many petitions never reach a courtroom at all.

The court waives the fee on hardship grounds.

Budget for the adviser rather than the court.

Can you file a Tax Court petition online?

Yes, through the court's electronic system, and from Britain that is plainly better than posting paper across the Atlantic. Electronic filing is timed in Washington, so a submission late on your evening may land the same day there. Check the time zone before cutting it fine.

Our guide to the IRS online account from the UK covers the other online channels.

File a fortnight early rather than testing the clock.

Who can represent you in the Tax Court?

Yourself, or somebody admitted to practise before the court. That is narrower than the ordinary tax world, because an enrolled agent or accountant who can handle an audit cannot argue a case here without separate admission. Many practitioners prepare the case and hand the hearing to counsel.

Our guide to IRS power of attorney covers ordinary representation.

Ask early whether your adviser is actually admitted.

What happens after you file?

The case usually goes back to appeals before a judge ever sees it, and most disputes end there. An independent officer reviews the file with an eye on how the case would actually go in court, which tends to produce a more realistic answer than the examiner gave.

Our guide to the Taxpayer Advocate Service covers a stalled file.

In our practice the great majority settle at that stage.

Will you have to travel to America?

Possibly not. Cases that settle need no appearance at all, and the court now hears many matters remotely. Where a trial is genuinely needed you choose a city for the session, and a judge travels there rather than you going to Washington.

Remote hearings have made this far easier from abroad.

Ask for a remote proceeding when you file if travel is hard.

What will the Tax Court not hear?

A good deal that expats care about. Foreign bank account report penalties sit outside the deficiency procedures, so they belong in a different court entirely. Many standalone information return penalties are the same, which catches people who assume one forum covers everything.

Our guide to delinquent FBAR submission covers those penalties.

Check which penalty you actually face before petitioning.

Does the Tax Court hear collection disputes?

Yes, through a separate route. Where you have asked for a collection hearing and disagree with the outcome, the court reviews that determination on its own short deadline. That is a different door into the same building, with a different clock on it.

Our guide to passport revocation for tax debt covers collection pressure.

The collection route has thirty days, not a hundred and fifty.

A worked example

Take an illustrative case. The IRS assesses an American in Bristol on an exclusion claim it says she cannot support.

The notice reaches her three weeks after its date, with 150 days running from the date itself.

She petitions in month three, which stops collection and routes the file to appeals.

Her travel diary persuades the appeals officer, and the case closes without a judge reading a page of it.

Does petitioning annoy the IRS?

No, and the worry stops people who ought to file. Petitions are an ordinary part of the system, and the case simply moves to a function whose job is to weigh it. Nothing about disputing an assessment marks your file for the future.

Thousands go in every year without consequence.

The only real cost is the time and the professional fee.

What should the petition say?

Which year is in dispute, which adjustments you disagree with, and why, in plain terms. It is a short document rather than a brief, and you are not expected to argue the whole case in it. Identifying every adjustment matters, because you concede anything you leave out.

List each adjustment separately rather than disputing the notice generally.

You can develop the reasoning later.

What evidence will matter?

The records that support whatever the IRS could not verify, which for expats is usually days, residence or foreign tax paid. Contemporaneous documents beat reconstructions comfortably. A diary kept at the time is worth more than a careful spreadsheet built three years later.

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

Gather the documents before you petition, not after.

Can you still use appeals first?

Usually you already have, because appeals normally comes before the deficiency notice. Where it did not, filing the petition routes you there anyway. So the two are sequential rather than alternatives, and petitioning does not close the door on a negotiated outcome.

Our guide to IRS letters after streamlined covers earlier correspondence.

Keep talking to the examiner while the clock runs.

What about penalties?

Penalties included in a deficiency notice come with it, so the court can consider them alongside the tax. Reasonable cause arguments are heard here as they would be anywhere. Where the only issue is a penalty assessed separately, the forum question returns.

Our guide to reasonable cause relief covers the argument.

An honest mistake abroad is a stronger story than it sounds.

Does a joint return complicate it?

It can, because both spouses are on the notice and both have the right to petition. Where one wants to dispute and the other does not, or where relief from a partner's error is in play, the case needs shaping before it is filed.

Our guide to innocent spouse relief covers that situation.

Decide jointly before either of you files anything.

What if the notice never reached you?

That happens to expats more than anybody, and it is why the address of record matters so much. A notice sent to your last known address starts the clock whether or not you saw it. Keeping that address current is the cheapest protection available.

Tell the IRS in writing every time you move.

A forwarding arrangement is not the same as updating the record.

How long does a Tax Court case take?

A settled case often closes within a year, and a tried case takes considerably longer. From abroad the correspondence adds time at every step, so plan on the longer end. Nothing moves to collection while it runs, which takes the urgency out of the wait.

A year is normal rather than slow.

Use the time to assemble the documents properly.

What records should you keep?

The notice itself with its envelope, proof of what you filed and when, every item of correspondence, and the evidence behind each disputed adjustment. Those four carry the case. Keep the envelope in particular, because the postmark occasionally matters.

Scan everything the day it arrives.

Keep the file intact until the case closes in writing.

Does the Tax Court see many foreign cases?

Enough that the judges know the territory. Exclusion claims, residence arguments and foreign tax credit disputes all turn up, and the court is used to records that came from another country. So you are not explaining the basics to somebody who has never met them.

British payslips and HMRC statements carry weight as evidence.

Translate nothing that is already in English, obviously.

What if the IRS is partly right?

That is the usual shape of a settlement. Few disputes end at nought or everything, and appeals weighs the chance of winning each adjustment rather than the file as a whole. So a case worth arguing on two points out of five still makes sense to bring.

Concede the weak points early and spend the effort on the strong ones.

A realistic opening position shortens the whole case.

Can you withdraw a Tax Court petition?

Not simply, and this surprises people. Once the court has the case, a withdrawal normally means a decision entering against you for the full amount. If you settle instead, the agreed figure goes in as the decision, which is the outcome you want.

Never file one you are not prepared to see through.

Settlement is the exit, not withdrawal.

Does a Tax Court case affect other years?

Only the years on the notice are before the court, but the reasoning spreads. An issue decided for one year usually settles how the IRS treats the same facts in the years either side. So the stakes are wider than the figure in dispute suggests.

Our guide to amending a US return covers correcting the other years.

Fix the later returns once the position is clear.

How to petition the Tax Court from the UK

1. Confirm the document really is a notice of deficiency.
2. Diarise the date on its face and count 150 days from it.
3. Decide whether the small case election suits your figures.
4. List every adjustment you intend to dispute.
5. File electronically rather than by international post.
6. Pay the $60 fee or ask for a waiver.
7. Expect the file to route to appeals and prepare for that.
8. Keep collection correspondence separate from the case.

Mistakes and penalties we see with Tax Court deadlines

The first is counting ninety days instead of a hundred and fifty, and filing far later than necessary out of panic.

The second is counting from the day the envelope arrived rather than the date printed on the notice.

The third is disputing the notice in general terms and conceding adjustments by failing to list them.

The fourth is petitioning over a penalty the court was never going to hear.

How US UK Tax Accountants helps

We diarise the date the day the notice lands, because everything else in this process can be fixed later and that one thing cannot.

Then we build the file appeals will actually read. Our US federal returns service covers the filings underneath it.

If a notice of deficiency has reached you in Britain, get in touch this week rather than next.

Last reviewed 27 October 2026. This article is general information and not personal tax advice, and court procedure turns on your own facts.