Can I use Form 843 to get back income tax I overpaid on a late US return?

No. The Form 843 instructions state the form must not be used for a refund or abatement of income, estate or gift tax, or to amend a previously filed income or employment tax return. If you missed a foreign tax credit, the foreign earned income exclusion or a treaty position, the correction goes on Form 1040-X. Form 843 reaches only the penalties, interest, additions to tax and certain fees connected with that return, not the tax itself.

I live in the UK and already paid a late-filing penalty. How long do I have to claim it back?

IRS Publication 556 states that you must generally file a claim for credit or refund within three years from the date you filed your original return or two years from the date you paid the tax, whichever is later. For a penalty paid in response to a notice long after the return was filed, the two-year leg from payment is frequently the only one still open. Living in the UK does not extend either period.

Can Form 843 recover an FBAR penalty?

Treat it as a separate matter. The FBAR is required under the Bank Secrecy Act, and Bank Secrecy Act penalties are imposed under Title 31 of the United States Code rather than the Internal Revenue Code. Form 843 is built around internal revenue taxes, penalties, interest, additions to tax and fees. An assessed FBAR penalty has its own assessment, appeal and collection process, so it should not be approached as a routine Form 843 claim.

Is not knowing about the US filing obligation enough for reasonable cause?

On its own, no. The IRS lists lack of knowledge of the filing requirement, mistakes and oversights, reliance on a tax professional and lack of funds as reasons that generally do not qualify. Ignorance is the outcome you must explain, not the explanation itself. What strengthens a claim is a specific documented circumstance such as serious illness, death in the family or an unavoidable absence, a tight chronology from discovery to filing, and evidence of ordinary care elsewhere, including a clean UK self assessment record.

What happens if the IRS disallows my Form 843 claim?

The IRS issues a notice of claim disallowance, usually Letter 105-C or Letter 106-C. You can submit further documentation, ask for the case to go to the IRS Independent Office of Appeals, or sue. Critically, you have two years from the date the notice of disallowance was mailed to file a refund suit in a United States District Court or the Court of Federal Claims, and that period does not pause while Appeals considers your case.

Missed US Tax Returns: Form 843 Refund Claims

Q: Does the streamlined programme refund penalties the IRS has already assessed?

No. The IRS confirms that for a qualifying Streamlined Foreign Offshore submission it will waive failure-to-file, failure-to-pay, accuracy-related, information return and FBAR penalties, but that any previously assessed penalties with respect to those years will not be abated. Streamlined protects the years in the submission going forward; it does not reverse assessments already made. Recovering a penalty you have already paid requires a separate refund claim on Form 843, argued on its own merits.

If you have brought missed US tax returns up to date from the UK and the IRS has already taken a penalty out of your account, Form 843 is the instrument that asks for the money back. Form 843, Claim for Refund and Request for Abatement, does two related but legally distinct jobs. It asks the IRS to abate a penalty that has been assessed but not yet paid, and it claims a refund of a penalty, addition to tax, interest or fee that has already been paid. The second job is the one most catch-up filers actually need, and it is the one most guidance handles badly. Once the money has left your account you are no longer asking for an administrative favour. You are making a statutory claim for refund, it is governed by a hard deadline, and if the IRS refuses it you have appeal rights and a litigation clock that starts running whether you use it or not.

In the catch-up work we prepare for UK-resident Americans, the pattern is depressingly consistent. Someone discovers the filing obligation late, files several years of returns without a structured relief position, receives a balance-due notice, pays it to make the problem go away, and only afterwards asks whether the penalty was ever properly due. By then the abatement conversation is over. The refund conversation has begun, and it runs on a different set of rules.

What Form 843 actually is, and what it is not

Form 843 is the general-purpose claim form for refunds and abatements of certain taxes, interest, penalties, fees and additions to tax. The IRS describes its purpose in exactly those terms at https://www.irs.gov/forms-pubs/about-form-843, and the current revision of the form is dated December 2024. It is a one-page form supported by a substantial set of instructions at https://www.irs.gov/instructions/i843, and the instructions matter far more than the form does, because most of the errors we see are jurisdictional rather than arithmetical.

The single most important thing to understand is the exclusion list. The instructions are explicit that Form 843 must not be used for a refund or abatement of income, estate or gift tax. It must not be used for the Additional Medicare Tax, for employer-side FICA, RRTA or income tax withholding, or to amend a previously filed income or employment tax return. It must not be used for instalment agreement fees, offer-in-compromise fees or lien fees. That first exclusion is the one that trips up catch-up filers most often.

Read carefully, the rule is narrower than it first appears. Form 843 does not reach the income tax shown on your return. It does reach the penalties and interest that were charged because of that return. If you filed a late 2021 Form 1040 from London, paid a failure-to-file penalty and a failure-to-pay penalty, and then realised you had also under-claimed foreign tax credits, you are looking at two separate corrections travelling on two separate forms. The under-claimed credits go on Form 1040-X. The penalties go on Form 843. Putting the income tax refund on Form 843 does not merely delay the claim, it invites a disallowance on a procedural ground that has nothing to do with the merits.

Abatement of an unpaid penalty versus refund of a paid one

The IRS treats these as one form and two remedies, and the difference is not cosmetic. Abatement is the removal of an assessed but outstanding liability. A refund is the return of money the government already holds. Abatement can often be handled informally. The IRS confirms at https://www.irs.gov/payments/penalty-relief that some penalty relief requests may be accepted over the phone using the number on your notice, and that where they cannot be, you may request relief in writing with Form 843. A refund of a paid penalty is different in kind. It is a claim for refund within the meaning of the Internal Revenue Code, it is subject to the limitation period in section 6511, and its denial produces formal appeal and litigation rights.

Practically, that means paying a penalty is not neutral. It converts a flexible administrative request into a formal claim with a countdown attached. It also, in our experience, changes the tone of the review. A penalty that is merely assessed can be removed by an IRS employee with relatively broad latitude. A penalty that has been paid must be given back, and the file is scrutinised accordingly.

Which penalties on missed US tax returns are Form 843 candidates

A UK-based late filer typically meets a predictable set of penalties. Knowing which ones are realistic Form 843 candidates saves a great deal of wasted effort.

Failure to file. The IRS states at https://www.irs.gov/payments/failure-to-file-penalty that the penalty is 5 percent of the tax due for each month or partial month the return is late, accruing to a maximum of 25 percent, with a minimum penalty where the return is more than 60 days late equal to a set amount or 100 percent of the underpayment, whichever is less. This is a core reasonable cause penalty and a strong Form 843 candidate.
Failure to pay. At https://www.irs.gov/payments/failure-to-pay-penalty the IRS gives the rate as 0.5 percent of unpaid tax per month or part month, capped at 25 percent, reduced to 0.25 percent per month during an approved payment plan where the return was filed on time, and increased to 1 percent per month if the tax remains unpaid 10 days after a notice of intent to levy. Also a reasonable cause penalty, though harder to win where funds existed.
Accuracy-related penalties. Available for reasonable cause where the taxpayer also acted in good faith.
Information return penalties. Form 5471 is the common one for business owners. The instructions at https://www.irs.gov/instructions/i5471 set the section 6038(a) penalty at 10,000 dollars for each annual accounting period of each foreign corporation, with a further 10,000 dollars for each 30-day period after a 90-day notice, limited to 50,000 dollars for each failure. Form 8938 penalties run up to 10,000 dollars with continuation charges to a stated maximum of 60,000 dollars.
Estimated tax penalty. The IRS is explicit at https://www.irs.gov/payments/penalty-relief-for-reasonable-cause that reasonable cause does not apply to certain penalties such as the estimated tax penalty. Do not build a claim around it.

One structural point that quietly determines how much work a claim involves. The instructions state that you must generally file a separate Form 843 for each tax period, fee year, or type of tax or fee. A four-year catch-up that produced failure-to-file and failure-to-pay penalties in each year is not one claim. It is a set of claims, each with its own period, its own amount and its own limitation date, sharing a common narrative attachment. The only meaningful exception is for interest assessments arising from a single IRS error or delay spanning several periods.

The route-selection map: when Form 843 is the right instrument

Most clients arrive convinced they need Form 843 when they need something else entirely, or convinced they need nothing when a claim is quietly expiring. This is the map we work from.

First-time abatement, penalty unpaid, clean history. The IRS sets out the criteria at https://www.irs.gov/payments/administrative-penalty-relief. It covers failure to file, failure to pay and failure to deposit, requires the same return type to have been filed on time for the prior three years with no penalty assessed other than the estimated tax penalty, and the IRS confirms you do not need to name FTA or supply documents. Phone the number on the notice first. Form 843 is the fallback in writing, not the starting point.
Reasonable cause, penalty unpaid. Write to the address on the notice, or use Form 843 where no notice route is available. The substance is identical to a refund claim; only the posture differs.
Reasonable cause, penalty already paid. This is Form 843 territory proper. Nothing else recovers the money, and the section 6511 clock is already running.
The income tax figure itself is wrong. Form 1040-X, not Form 843. A missed foreign tax credit, an unclaimed foreign earned income exclusion, an overstated capital gain, a treaty position that should have been taken. Form 843 is generally not the route to claim a refund of income tax shown on a return.
The penalty was never legally assessable. A refund claim on Form 843 is still the vehicle, but the ground is legal rather than factual, and the argument should be pleaded as such rather than dressed up as reasonable cause.
The IRS has already refused you once. Not a fresh Form 843. Escalate the existing claim to the IRS Independent Office of Appeals, and watch the suit deadline described below.

The most expensive mistake in this list is the fourth. Filing Form 843 for an income tax overpayment burns months, and if the section 6511 window closes on the correct form while the wrong one is in the queue, the money is gone.

Reasonable cause that survives contact with an examiner

Reasonable cause is the substantive ground behind almost every Form 843 claim a catch-up filer will make. The IRS explains at https://www.irs.gov/payments/penalty-relief-for-reasonable-cause that reasonable cause is determined on a case-by-case basis considering all the facts and circumstances, and that it can apply to failure to file, failure to pay, accuracy-related and information return penalties. It also publishes the list of things that generally do not qualify, and that list is where most claims written from abroad fall apart.

The IRS names four categories that generally do not work: reliance on a tax professional, since you are generally responsible for complying with tax law even if someone else handles your taxes; lack of knowledge of the filing requirement; mistakes and oversights; and lack of funds, which the IRS states is not reasonable cause for failing to pay or deposit taxes. Notice how much of the standard expat narrative that removes. I did not know US citizens have to file from abroad is, standing alone, the weakest possible statement. It is an admission of exactly the category the IRS has already excluded.

What distinguishes a credible statement from a boilerplate one is that a credible statement explains why an ordinarily careful person in the same position would have failed to discover or discharge the obligation, and then evidences it. Ignorance is the outcome, not the cause. The cause is what you have to describe.

A specific triggering circumstance with dates. Serious illness, a death in the family, an unavoidable absence, a documented disruption. The IRS itself lists fires, natural disasters or civil disturbances, death, serious illness or unavoidable absence, and system issues that delayed a timely electronic filing or payment as circumstances it accepts.
A continuous chronology. What you knew, when you knew it, what you did within what period, and why the gap between discovery and filing is short. A long unexplained gap between finding out and acting undoes an otherwise strong case.
Corroboration held by someone other than you. UK medical records, NHS correspondence, hospital discharge letters, HMRC correspondence, employer relocation documents, immigration and travel records, probate or care documents, bank records showing the account you did not know was reportable was dormant.
Evidence of ordinary business care in your other affairs. A UK self assessment filing history without penalties, PAYE compliance, timely Companies House filings. This is the single most underused evidence in expat claims and it directly answers the ordinary business care and prudence test.
The absence of any indicator of willfulness. No account closures on discovering the obligation, no structuring of deposits, no shift of assets between institutions, no use of nominee arrangements.

Assertions that do not help, in our experience of drafting these: that the rules are complicated; that no employer or bank told you; that you have always paid UK tax in full and therefore owed nothing to the United States, which conflates the tax result with the filing duty; that other Americans in the UK do not file either; and any version of blaming an accountant, which the IRS has already told you it will not accept as a general matter. Where professional failure genuinely is central, the facts have to be extraordinary and documented, not asserted.

One drafting discipline that consistently improves outcomes. Write the statement so that it can be read alone, without the return package, and still make sense. It should identify the taxpayer, the period, the penalty, the code section, the facts, the evidence attached and the relief sought, in that order. The examiner reading it may never see the underlying return.

Can you get the interest back as well?

Usually not on its own terms, and the grounds are much narrower than most readers expect. The IRS states at https://www.irs.gov/payments/interest that it may reduce the amount of interest you owe only if the interest is applied because of an unreasonable error or delay by an IRS officer or employee. The Form 843 instructions frame the same rule by reference to section 6404(e): the error or delay must relate to the performance of a managerial or ministerial act, you must not have caused any significant aspect of that error or delay, and the relief is limited to taxes for which a notice of deficiency is required.

A managerial act is an administrative act during the processing of your case involving temporary or permanent loss of records or the exercise of judgment or discretion relating to management of personnel. A ministerial act is a procedural or mechanical act not involving judgment or discretion, occurring after all prerequisites such as conferences and supervisory review have taken place. Neither definition covers the ordinary passage of time while you were not filing. Interest that accrued because a return was late is simply the price of the delay.

The good news is mechanical. The IRS confirms on the same page that if you reduce the amount of tax or penalties you owe, by filing an amended return or by qualifying for penalty relief, it will automatically reduce the related interest. So a successful penalty claim carries its interest with it. You do not generally need a separate interest argument, and building one where the facts do not support it weakens the penalty claim it is attached to.

The refund window: how the deadline runs from filing and from payment

This is the fact that decides whether a claim exists at all. IRS Publication 556, at https://www.irs.gov/publications/p556, states the rule plainly: generally, you must file a claim for a credit or refund within 3 years from the date you filed your original return or 2 years from the date you paid the tax, whichever is later. Section 6511 is the underlying provision, and the Form 843 instructions repeat the same test.

Two features of that rule matter disproportionately for late filers. First, the three-year leg runs from when the return was actually filed, not from the original due date, which for someone who filed a 2017 return in 2024 is a meaningful extension rather than a bar. Second, the two-year leg runs from payment, and for a penalty paid in response to a notice long after the return went in, the two-year leg is often the only one still open. Where the three-year leg has closed and only the two-year leg remains, the amount recoverable is also limited by reference to what was paid in that window.

Because the clock runs per payment as well as per period, a multi-year catch-up can have several different expiry dates. We date-schedule them at the outset. The practical rule we work to is simple: identify the earliest expiring claim in the file and work backwards from it, rather than starting with the largest penalty.

Where Form 843 goes, and why it is not where your return goes

There is no single Form 843 address, and this catches people out constantly. The instructions make the destination depend on the reason for the claim. If you are filing in response to an IRS notice, use the address shown on that notice. If you are not, use the service centre appropriate to the underlying tax. Specialised categories have their own dedicated addresses. A claim posted to the address you used for your Form 1040 is not fatal, but it can add months, and from the UK those months are on top of international mail time.

A few mechanical points that avoid rework. If a representative signs or files on your behalf, Form 2848 must be attached. On a joint return both spouses sign. The claim needs the type of tax or fee, the period, the amount and, for a penalty claim, the Internal Revenue Code section under which the penalty was imposed, which you will find on the notice. Send everything by a service that produces proof of dispatch and delivery, and keep the complete package. In a dispute two years later, the date you can prove is worth more than the argument you can remember.

A worked scenario

The following figures are illustrative only. A London-based founder, a US citizen, discovers in 2023 that she has never filed US returns. She files four years of Forms 1040 herself, without any relief position and without considering a formal catch-up route. Two of the years show a small balance due after foreign tax credits because of a UK dividend timing difference. The IRS assesses failure-to-file and failure-to-pay penalties plus interest on those two years, issues a notice, and she pays the full amount in early 2024 to close it down. In 2026 she asks whether that was necessary.

The analysis runs as follows. The income tax itself was correctly computed, so there is nothing for Form 1040-X to do. The penalties were paid, so abatement is unavailable and a refund claim on Form 843 is the only route. Because each year is a separate period, two claims are prepared, each identifying the penalty code section from the notice, each attached to a single common reasonable cause narrative covering a documented eighteen-month period of serious illness that overlapped the discovery and filing window, supported by UK medical records and a clean UK self assessment history. Interest is not separately argued, because there was no IRS error or delay, and any interest attributable to abated penalties follows automatically. The claims are dated against both the three-year and two-year legs of section 6511, and the earlier of the two expiry dates governs the filing order.

When the claim is denied: appeals and the clock nobody watches

If the IRS refuses all or part of the claim it issues a notice of claim disallowance, generally Letter 105-C for a full disallowance or Letter 106-C for a partial one. The Taxpayer Advocate Service explains the consequences at https://www.taxpayeradvocate.irs.gov/notices/notice-of-claim-disallowance/. You may supply further documentation to the address on the letter, you may ask that the case go to the IRS Independent Office of Appeals, which is described at https://www.irs.gov/appeals and exists to resolve disputes without litigation in a way that is fair and impartial to the government and to you, or you may sue.

Here is the trap. You have 2 years from the date of mailing of the notice of disallowance to file a refund suit in a United States District Court or in the United States Court of Federal Claims, and that two-year period is not extended while the IRS reconsiders the claim or while it sits with Appeals. Publication 556 also confirms that if the IRS does not act on a claim within 6 months from the date you filed it, you may file suit without waiting for a decision. A claim can therefore be working its way politely through Appeals while the only deadline that ultimately protects it quietly expires. We diary the disallowance date the day the letter arrives, not the day the Appeals conversation ends.

How this interacts with a streamlined submission

The Streamlined Foreign Offshore Procedures are designed so that these penalties never arise. The IRS states at https://www.irs.gov/individuals/international-taxpayers/u-s-taxpayers-residing-outside-the-united-states that for a qualifying submission it will waive failure-to-file and failure-to-pay penalties, accuracy-related penalties, information return penalties and FBAR penalties. Eligibility requires non-residency, meaning in one of the most recent three years no US abode and physical presence outside the United States for at least 330 full days, a Form 14653 certification that the non-compliance resulted from non-willful conduct, three years of delinquent or amended returns and six years of FBARs, with the returns marked Streamlined Foreign Offshore in red.

Then comes the sentence that makes Form 843 necessary. The same IRS page states that any previously assessed penalties with respect to those years will not be abated. Streamlined prevents penalties prospectively for the years in the submission; it does not undo assessments the IRS has already made. Someone who files four years alone, collects penalties, pays them, and then enters streamlined has not recovered anything. The paid penalties sit outside the programme, and the only route back to them is a claim for refund on Form 843, argued on its own merits and inside its own limitation period.

This is precisely why the sequencing of a catch-up matters more than the paperwork. Filing quietly first and considering the programme afterwards converts a waiver into a contested refund claim. The general procedures page at https://www.irs.gov/individuals/international-taxpayers/streamlined-filing-compliance-procedures should be read before the first return goes in, not after the first notice arrives.

FBAR penalties sit outside this machinery

Be careful here, because a great deal of published commentary is loose about it. The FBAR is required under the Bank Secrecy Act, as the IRS confirms at https://www.irs.gov/businesses/small-businesses-self-employed/report-of-foreign-bank-and-financial-accounts-fbar, which also gives the 10,000 dollar aggregate account threshold and the 15 April due date with an automatic extension to 15 October. Bank Secrecy Act penalties are imposed under Title 31 of the United States Code, not under the Internal Revenue Code, and Form 843 is built around refunds and abatements of internal revenue taxes, penalties, interest, additions to tax and fees.

The practical consequence is that an assessed FBAR penalty is not a straightforward Form 843 matter and should not be treated as one. It has its own assessment, appeal and collection process, and the strategy for challenging it is different. A separate point of currency for anyone reading older material: the IRS withdrew its Delinquent FBAR Submission Procedures page around 1 July 2026, so that is no longer a live named route. Late FBARs are filed through FinCEN's BSA E-Filing System with a reason for late filing, or within the Streamlined Filing Compliance Procedures where the taxpayer qualifies. The IRS FBAR page itself now simply directs taxpayers who have not been contacted and are not under investigation to file late FBARs as soon as possible to keep potential penalties to a minimum.

One live IRS channel worth knowing about

The IRS has published a dedicated route for Form 843 claims relating to fully paid interest and penalties that cite Kwong v. United States, set out at https://www.irs.gov/forms-pubs/filing-form-843-for-claims-citing-kwong-v-united-states. Paper claims go to Internal Revenue Service, 1973 N Rulon White Blvd., Ogden, UT 84201, and must be annotated Kwong vs. United States across the top of the form. Individual taxpayers with an IRS Online Account may submit electronically through the IRS forms page. It is a narrow, litigation-driven channel rather than a general relief programme, and section 6511 still governs whether a claim is timely, but it illustrates the wider point: Form 843 is the vehicle the IRS itself designates when money has already been paid and has to come back.

What we do with these files

In practice the work divides into three parts, in this order. First, dating. Every paid penalty in the file is scheduled against both legs of the section 6511 test, and anything approaching expiry is prepared first regardless of size. Second, routing. Each item is assigned to first-time abatement, a reasonable cause request, a Form 843 refund claim, a Form 1040-X, or Appeals, because a well-argued claim on the wrong form is worth nothing. Third, evidence. The narrative is drafted once, corroborated with third-party documents, and attached to every period it supports.

If you are still deciding how to approach the underlying catch-up rather than the penalties, our pages at us-uktax.com/irs-streamlined-filing and us-uktax.com/streamlined-foreign-offshore-procedures set out the qualifying route, and the streamlined filing calculator at us-uktax.com/calculators/streamlined-filing-calculator gives an initial sense of scope. The broader US compliance work sits at us-uktax.com/us-tax-services and us-uktax.com/cross-border-tax-planning, and the position work for substantial cross-border wealth sits at us-uktax.com/divisions/high-net-worth. The single sentence worth carrying away is this: paying an IRS penalty to make a notice go away does not end the matter, but it does start a clock, and the clock does not care that you were living in London when it started.