Notice of Deficiency: Your Ticket to the Tax Court From Britain
A notice of deficiency is the formal letter in which the IRS determines that you owe more US tax and proposes to assess it. Furthermore, it is the single most important letter an American in Britain can receive from the IRS. It opens your only route to the US Tax Court without paying first, and it starts a deadline that courts treat with extraordinary strictness.
For Americans living in the UK, that deadline runs to 150 days rather than the familiar 90. However, the extra time comes with a sting. As we explain below, a missed deadline is probably fatal for a taxpayer with no US home, even though several American appeals courts have softened the rule for domestic filers. At TaxYork we treat every such letter as an emergency.
What a Notice of Deficiency Actually Is
A notice of deficiency, often called a statutory notice or a 90-day letter, is required by law before the IRS can assess most additional income tax. The IRS issues it on Letter 3219 or a similar form, and it sets out the proposed tax, penalties and the last date to petition. The Internal Revenue Manual on statutory notices governs how examiners prepare it.
Critically, the letter is not a bill. Instead, it is a legal determination that becomes a bill only if you let the deadline pass.
Why the IRS Must Send One Before Assessing
Congress built a pre-payment forum into the US system. Under section 6213, the IRS generally cannot assess a deficiency, or levy to collect it, until the petition period ends. Moreover, if you petition in time, assessment waits until the Tax Court decision becomes final.
That protection is valuable. Consequently, the notice of deficiency is the moment when your negotiating position is at its strongest.
How It Differs From Earlier IRS Letters
Most cases produce earlier correspondence first. For example, an examination usually ends with a thirty-day letter offering an administrative appeal, and a non-filer case begins with Letter 2566. By contrast, the notice of deficiency is the final step before assessment. Our guide to the IRS substitute for return process explains how non-filer cases reach this stage.
The 150-Day Rule for Americans Abroad
Section 6213(a) gives 90 days to petition, or 150 days where the notice of deficiency is addressed to a person outside the United States. That single sentence governs every Tax Court case brought from Britain.
What "Addressed to a Person Outside the United States" Means
The Tax Court reads the phrase generously. In Estate of Krueger, decided in 1960, it refused to limit the longer period to people settled abroad. Instead, it held that temporary absence can qualify too.
Later cases have extended the rule to taxpayers travelling when the notice arrived. Nevertheless, the outcome turns on facts, including whether the absence actually hampered a timely response. Therefore, never rely on the 150-day period if you can meet the 90-day one.
Always Petition by the Date Printed on the Notice
Every notice of deficiency states the last day to file a petition. Helpfully, section 6213(a) treats a petition filed by that printed date as timely, even if the IRS calculated it wrongly. Accordingly, the printed date is your safest anchor.
Where the printed date shows 90 days but you live in Britain, file within 90 days anyway. Arguing afterwards about the 150-day rule is expensive and uncertain.
The Last Known Address Trap
A notice of deficiency is valid if mailed to your last known address, whether or not it reaches you. Section 6212 sets that rule. Usually, the last known address is the one on your most recently filed return.
Here lies the classic expatriate problem. A move within London, or from New York to Surrey, leaves the IRS writing to an empty flat. Filing Form 8822 to change your address the moment you move is the cheapest protection available.
Is a Missed Deadline Fatal? The 2026 Circuit Split
For decades, every appeals court treated the petition deadline as jurisdictional. In other words, a court could not hear a late petition, whatever the excuse. That consensus has now fractured, and the fracture matters enormously for Americans abroad.
The Circuits That Now Allow Equitable Tolling
In Culp, decided in 2023, the Third Circuit held that the deadline is a claim-processing rule rather than a jurisdictional bar. Consequently, a court may extend it where a diligent taxpayer faced extraordinary circumstances. The Second Circuit agreed in Buller in 2025, as the Journal of Accountancy's summary of Buller reports. Similarly, the Sixth Circuit followed in Oquendo, and the Eighth Circuit joined in Maniktala in August 2026.
Kyick Holdings and the Circuits That Refuse
On 17 August 2026, the First Circuit took a middle path in Kyick Holdings, as this analysis of the Kyick Holdings decision explains. It agreed that the deadline is not jurisdictional. However, it held that the deadline is mandatory and cannot be equitably tolled. Tellingly, Kyick lost because its IRS notice, mailed to its last known address, came back undelivered and arrived too late.
Meanwhile, the Seventh, Ninth and Eleventh Circuits continue to treat the deadline as jurisdictional. As a result, the law now depends heavily on which circuit hears your appeal.
Why Americans in London Probably Face the Strictest Rule
Here is the point no domestic guide addresses. Under section 7482, an individual's appeal goes to the circuit of their legal residence. If no circuit applies, the default is the Court of Appeals for the District of Columbia.
An American living permanently in Britain often has no US legal residence at all. Therefore, the D.C. Circuit is the likely appellate forum, and it has not yet resolved the question. Meanwhile, the Tax Court itself held in Hallmark Research Collective in 2022 that the deadline is jurisdictional. It reaffirmed that view by an eleven-to-two vote in Sanders in 2025.
The practical conclusion is stark. For most Americans in the UK, a late petition following a notice of deficiency will almost certainly be dismissed. Accordingly, treat the deadline as absolute.
If You Still Keep a US Home
Some Americans in Britain retain a legal residence in a US state, often to preserve a Florida or Texas domicile. In that case, your appeal follows that state's circuit instead of the D.C. Circuit. Unfortunately, Florida sits in the Eleventh Circuit, which still treats the deadline as jurisdictional. Consequently, a Florida domicile offers no rescue for a late petition either.
Filing a Tax Court Petition From Britain
The mechanics of filing from overseas create avoidable risks. Fortunately, each one has a simple solution.
Electronic Filing Beats Royal Mail
The United States Tax Court accepts petitions electronically through its DAWSON system. We recommend e-filing for every client abroad.
The reason is the timely-mailing rule. Section 7502 treats a petition as filed on its postmark date only for US postmarks and certain designated private delivery services. By contrast, a Royal Mail postmark earns no such protection. Hence a petition posted in London on day 148 may arrive late and fail.
What to Do in the First Seventy-Two Hours
Speed decides these cases more often than substance. First, photograph the envelope and note the date you received it, because the postmark and delivery date may later matter. Next, find the last date to petition printed on the notice of deficiency and diarise it at least a fortnight early.
Additionally, request your IRS account transcripts and the examination report behind the letter. Finally, instruct a representative on Form 2848 so that the IRS can discuss the case with someone who is awake during American office hours.
The Small Tax Case Procedure
Disputes of $50,000 or less per year may use the small tax case procedure. The process is simpler, the rules of evidence are relaxed, and hearings move faster. Nevertheless, small case decisions cannot be appealed, so the choice deserves thought where the principle matters more than the amount. The filing fee is $60.
Remote Hearings and Settlement Through Appeals
Litigating from Britain is far less daunting than clients fear. The Tax Court conducts many proceedings remotely by video, which spares transatlantic travel. Moreover, docketed cases are normally referred to the IRS Independent Office of Appeals for settlement discussions before any trial.
In practice, the great majority of Tax Court cases settle. Consequently, filing the petition is often the step that finally brings a reasonable IRS negotiator to the table.
Your Other Options After a Notice of Deficiency
A petition is not the only response. However, each alternative carries costs that you should weigh carefully.
Agreeing to the Deficiency
If the adjustment is right, you can sign the waiver form enclosed with the notice of deficiency. The IRS then assesses promptly, which stops further arguments but not interest. The Taxpayer Advocate Service guidance on the 90-day notice describes this route.
Paying First and Suing for a Refund
Alternatively, you can pay the full amount and claim a refund, then sue in a US district court or the Court of Federal Claims. However, the full-payment rule requires the entire assessed tax first. For most high-net-worth clients, tying up that capital in dollars makes the Tax Court the better forum.
Penalties and Interest Inside the Notice
Most notices include an accuracy-related penalty of 20 per cent of the underpayment. However, that penalty is itself open to challenge in the Tax Court, and reasonable cause frequently defeats it where cross-border rules are genuinely complex. Meanwhile, interest runs from the original due date of the return, not from the date of the notice of deficiency.
Therefore, a prompt payment on account of any undisputed element can stop interest accruing on that portion. We often recommend such a deposit while contesting the remainder, because it does not waive your right to petition.
What Happens to the Statute of Limitations
Issuing a notice of deficiency suspends the IRS assessment period. Section 6503 pauses the clock for the petition period, throughout any Tax Court case, and for sixty days afterwards. Therefore, a petition never lets an assessment window expire by accident.
HMRC Appeals: How the British System Compares
Britain handles disputed tax very differently, and dual filers should understand both systems before responding to either.
Thirty Days and a Statutory Review
HMRC gives you 30 days to appeal a tax decision, counted from the date on the letter rather than the date you receive it. HMRC then offers a statutory review, or you may go directly to the First-tier Tribunal. In contrast to the US, you appeal to HMRC first before reaching the tribunal.
Payment Postponed, Late Appeals Possible
For direct taxes, HMRC usually postpones payment of the disputed tax until the appeal concludes. Moreover, the tribunal can admit a late appeal where a judge considers it in the interests of justice. Hence the British system forgives lateness far more readily than a notice of deficiency does.
Why the Two Systems Interact
A US adjustment frequently reflects a disagreement about UK tax paid. For example, the IRS may deny a foreign tax credit because it doubts the UK figure. Consequently, HMRC records often form the core evidence in a Tax Court case, and we assemble them early.
A Worked Case Study: 150 Days That Saved a Credit
Consider Catherine, an American partner at a London law firm. Her 2023 US return claimed foreign tax credits of $84,000, including a carryover from earlier years. The IRS examined the return and disallowed the carryover, believing it unsupported.
The IRS issued a notice of deficiency dated 3 March 2026 for $84,000 of tax plus a $16,800 accuracy penalty. Unfortunately, Catherine had moved flats within London in 2025 without telling the IRS. The letter reached her through a forwarding service on 21 June, day 110.
Under a 90-day rule she would have been out of time. Instead, the notice was addressed outside the United States, so the 150-day period ran to 31 July. She instructed us on 23 June.
We filed her petition electronically through DAWSON on 30 June, a full month before the deadline. Subsequently, the case went to Appeals. We supported the carryover with her UK tax calculations, HMRC statements and the prior Forms 1116 that established the unused credits.
Appeals accepted almost the entire carryover. Ultimately, the case settled at $3,100 of additional tax with no penalty, a saving of roughly $97,700. Had the letter arrived on day 151, the full $100,800 would have been assessed without any Tax Court hearing.
How TaxYork Can Help
We represent Americans in Britain from the first examination letter through to Tax Court settlement. Furthermore, we treat every notice of deficiency as a deadline-first matter, calculating the petition date on the day we receive it.
Our work covers the technical substance too. We rebuild foreign tax credit and treaty positions with UK evidence, prepare any missing returns, and bring related FBAR and FATCA filings current through our FBAR and FATCA reporting team. Additionally, we update your IRS address so that future letters reach you in Britain.
Conclusion
A notice of deficiency gives Americans abroad 150 days, which sounds generous until you consider the rest of the picture. Letters go to stale addresses, Royal Mail postmarks earn no protection, and the courts most likely to hear your case treat the deadline as absolute. Therefore, act on the day the letter arrives. Above all, file electronically and file early. Professional bodies such as the ICAEW and the Chartered Institute of Taxation consistently stress specialist support for cross-border disputes, and this area shows why.
Contact Us
If you have received a notice of deficiency, or any IRS letter proposing additional tax, speak to us immediately. You can book a consultation and we will confirm your deadline the same day.
Email hello@taxyork.com or telephone 020 3488 8606.
Disclaimer
This article provides general information about the notice of deficiency process and US-UK cross-border taxation. It does not constitute tax, legal or financial advice, and it does not create a professional relationship. Tax law and court decisions change frequently, and outcomes depend entirely on individual facts. Accordingly, you should obtain advice specific to your circumstances before acting. TaxYork accepts no liability for action taken or omitted in reliance on this article.