How does a missed Form 5471 affect my foreign tax credit?

Under IRC section 6038(c)(1), the foreign taxes paid by the foreign corporation, and the taxes deemed paid by you under section 960 with respect to it, are reduced by 10 percent for the year of the failure. If the failure continues 90 days or more after the IRS mails notice, an additional 5 percent is removed for each three-month period, or fraction of one, that it continues. The reduction is capped under section 6038(c)(2) at the greater of USD 10,000 or the income of the foreign corporation for that annual accounting period.

Is the section 6038(c) foreign tax credit reduction separate from the USD 10,000 Form 5471 penalty?

They are separate sanctions in separate subsections, but they are not fully cumulative. Section 6038(b) imposes the USD 10,000 monetary penalty per corporation per annual accounting period, with an additional USD 10,000 for each 30-day period after the 90-day notice period, capped at an additional USD 50,000. Section 6038(c) imposes the credit reduction. IRC section 6038(c)(3) then decreases the credit reduction by the dollar amount of the section 6038(b) penalty imposed for the same failure.

Can the IRS deny 100 percent of my foreign tax credits for a late Form 5471?

Not immediately, and not in the way that phrase suggests. The reduction starts at 10 percent and only grows by 5 percent per three-month period once the IRS has mailed notice and 90 days have run, so reaching a total disallowance would require years of continued failure after a notice. The amount removed is also capped by IRC section 6038(c)(2). Filing the return stops the escalation.

Does the section 6038(c) cut apply to the UK income tax I pay personally?

No. The reduction in IRC section 6038(c)(1) operates on tax paid by the foreign business entity and on tax deemed paid under section 960 with respect to it. UK income tax you pay in your own name on salary or dividends is your own tax, credited on your own return, and is outside that pool. The clients most exposed are those relying on a section 962 election, because that election is what turns the company's UK corporation tax into a deemed-paid credit on an individual return.

Does a missed Form 5471 keep my whole tax return open to audit?

IRC section 6501(c)(8)(A) provides that the assessment period does not expire before three years after the required information is furnished, so an unfiled Form 5471 holds the year open indefinitely. Section 6501(c)(8)(B) limits that extension to the items related to the failure where the failure was due to reasonable cause and not willful neglect, which is one of the strongest practical reasons to document reasonable cause properly.

Does the Farhy litigation mean the IRS cannot come after me over Form 5471?

No. The Farhy and Mukhi decisions concern whether the section 6038(b)(1) monetary penalty can be assessed under the assessable penalty procedures, and the DC Circuit reversed the Tax Court on that point on 3 May 2024. None of it touches the section 6038(c) foreign tax credit reduction, which operates as an adjustment to how sections 901 and 960 apply to you rather than as an assessable penalty, and none of it affects the section 6501(c)(8) extension of the assessment period.

Form 5471 Penalties: The Section 6038(c) FTC Cut

A late or incomplete Form 5471 does not only trigger the USD 10,000 monetary penalty that most guides describe. Under IRC section 6038(c), the IRS can separately reduce the foreign income taxes you are permitted to credit against your US tax by 10 percent, with a further 5 percent removed for each three-month period the failure continues once a 90-day notice period has expired. That reduction is a distinct sanction from the section 6038(b) dollar penalty. It is computed as an adjustment to your tax, not billed as a penalty notice, and for a US owner of a profitable UK limited company it is often the more expensive of the two.

In practice we see this play out in a particular way. A US citizen or green card holder living in London owns all of the shares in a UK trading company. The company pays UK corporation tax at 25 percent. The shareholder has been filing Form 1040 and claiming credit for UK tax, but nobody ever prepared the information return for the company. Three or four years later the position surfaces, usually during a mortgage application, a fund subscription, or a sale process. At that point the client has been told to expect USD 10,000 a year. What they have not been told is that the credits they were relying on to keep their US bill at zero can be trimmed under a completely different subsection of the same statute, and that the two sanctions interact in a way that changes the arithmetic.

What is the section 6038(c) penalty for a late Form 5471?

The section 6038(c) penalty is a mandatory percentage reduction in the foreign income taxes a US person may take into account for foreign tax credit purposes, imposed because the person failed to furnish the information required by section 6038(a) within the prescribed time. The information required by section 6038(a) about a foreign corporation is furnished on Form 5471. Miss it, file it late, or file it without the schedules that make it substantially complete, and the reduction is in scope.

The mechanics set out in IRC section 6038(c)(1) and mirrored in Treasury Regulation section 1.6038-2(k) are precise. For the taxable year of the failure, in applying section 901, the taxes paid by the foreign business entity are reduced by 10 percent, and the taxes deemed paid under section 960 with respect to that entity are reduced by 10 percent. If the failure continues 90 days or more after the date the IRS mails notice of the failure, an additional 5 percent reduction applies for each three-month period, or fraction of one, during which the failure continues after that 90-day period expires.

Two features of that language matter more than the headline percentage. First, the reduction runs against taxes of the foreign entity, not against every foreign tax on your return. Second, the additional 5 percent tranches only begin once the IRS has actually mailed notice and 90 days have run. Until that notice goes out, the exposure is the flat 10 percent, however many years have passed since the original due date.

How is the Form 5471 foreign tax credit reduction calculated?

Work through it as a sequence rather than as a single percentage. Each step is separately capable of changing the answer, and skipping straight to a headline number is how practitioners overstate the exposure to clients.

Identify the failure. Each foreign corporation and each annual accounting period is its own failure. A US shareholder in two UK companies with three unfiled years has six failures, not one.
Identify the pool of taxes attached to that failure. This is the foreign income tax paid or accrued by the foreign corporation for the relevant annual accounting period, and the amount of that tax deemed paid by you under section 960.
Apply the 10 percent reduction to that pool for the taxable year in which the failure exists.
Add 5 percent for each three-month period, or part of one, that the failure continues after the 90-day period following the IRS notice has run.
Cap the result under IRC section 6038(c)(2). The reduction cannot exceed the greater of USD 10,000 or the income of the foreign business entity for the annual accounting period concerned.
Net off the dollar penalty under IRC section 6038(c)(3). The reduction is decreased by the dollar amount of any section 6038(b) penalty imposed for the same failure.
Check IRC section 6038(c)(4)(A). The same taxes cannot be reduced more than once for the same failure, which prevents the same UK corporation tax being cut twice where it flows through more than one route.

The percentage can build over time. A failure that continues for years after a notice has been issued accretes 5 percent every quarter, and the arithmetic will eventually reach the point where the entire relevant tax pool is disallowed. But the statute never simply switches off your foreign tax credits on day one, and describing it that way to a client is both wrong and unhelpful, because it obscures the fact that the clock is stopped by filing.

Which foreign taxes does the section 6038(c) reduction actually hit?

This is the point competitor guides consistently blur, and it decides whether a given client is exposed at all. The reduction operates on tax paid by the foreign business entity and on tax deemed paid under section 960 with respect to it. It does not reach into the rest of your credit position.

UK corporation tax paid by your UK limited company on its own profits is squarely within the reduction where it reaches your return as a deemed-paid credit.
UK income tax you pay personally on a salary drawn from that company is your own tax, credited under section 901 on your own return, and is not the entity-level tax that section 6038(c) reduces.
UK income tax you pay personally on a dividend from the company is likewise your own tax and sits outside the entity-level pool.
Credits claimed on a section 962 election are the most exposed of all, because that election is precisely what converts the company's UK corporation tax into a section 960 deemed-paid credit on an individual's return.
Foreign tax on unrelated income, such as UK tax on rental profits or on an unrelated employment, is untouched by a Form 5471 failure.

The consequence is counter-intuitive. The US owner of a dormant or loss-making UK company faces the section 6038(b) dollar penalty and essentially no section 6038(c) exposure, because there is no meaningful pool of entity-level tax to reduce. The US owner of a highly profitable UK trading company who has built their entire US position on a section 962 election and section 960 credits faces a section 6038(c) reduction that can dwarf the dollar penalty. High-earning business owners and investors are therefore the group with the most at stake, which is the opposite of the impression left by guides that treat the reduction as a footnote.

The two limits nobody explains: section 6038(c)(2) and section 6038(c)(3)

IRC section 6038(c)(2) caps the reduction for each failure at the greater of USD 10,000 or the income of the foreign business entity for the annual accounting period in which the failure occurs. For a small UK company the USD 10,000 floor is often the operative figure and the exposure is contained. For a company with several hundred thousand pounds of profit the cap is set by the company's own income and will not bind at all, because the percentage reduction of its corporation tax will never approach its total income. Knowing which side of that line a client sits on is the first thing to establish before quoting an exposure.

IRC section 6038(c)(3) is the coordination rule and it is genuinely favourable. The amount of the credit reduction for a failure is decreased by the dollar amount of the section 6038(b) penalty imposed with respect to that same failure. In other words, the USD 10,000 you are billed for the missing Form 5471 is credited against the value of the foreign tax credit the IRS is taking away for the same year and the same corporation. The two sanctions are not purely cumulative. Where the entity-level tax pool is modest, the dollar penalty can absorb the credit reduction entirely.

We routinely see exposure estimates prepared without either rule applied. That produces figures that are too high, drives clients toward unnecessarily aggressive remediation choices, and undermines the credibility of the reasonable cause narrative that will eventually be put in front of the IRS.

How the 90-day notice and the three-month clock actually run

Both the escalating dollar penalty in IRC section 6038(b)(2) and the escalating credit reduction in section 6038(c)(1) hang off the same event: the IRS mailing notice of the failure to the person required to furnish the information. Nothing escalates before that. The dollar penalty then runs at an additional USD 10,000 for each 30-day period, or fraction of one, capped at an additional USD 50,000 for each annual accounting period. The credit reduction runs at an additional 5 percent for each three-month period, or fraction of one.

Note the different cadences. The dollar penalty escalates monthly and stops at a statutory ceiling. The credit reduction escalates quarterly and has no percentage ceiling of its own, only the section 6038(c)(2) cap on the amount. Over a long stand-off the dollar penalty reaches its maximum and stays there while the credit reduction keeps climbing. That is why a client who has received a notice should not be allowed to let a filing sit while correspondence goes back and forth. Filing the return stops both clocks.

Why the Farhy litigation does not protect you from the section 6038(c) cut

Since 2023 a great deal has been written about whether the IRS may assess section 6038(b)(1) penalties at all. The Tax Court held in Farhy v. Commissioner in April 2023 that it may not. The Court of Appeals for the DC Circuit reversed that decision on 3 May 2024. The Tax Court then reaffirmed its own position in Mukhi v. Commissioner in November 2024, leaving a genuine split that taxpayers outside the DC Circuit continue to litigate.

That entire line of authority is about assessment authority for a penalty. The section 6038(c) reduction is structurally different. It does not impose a penalty that has to be assessed under the assessable penalty machinery; it changes how section 901 and section 960 are applied to you, which changes your tax. An adjustment of that kind reaches you through ordinary deficiency procedures. A taxpayer who is relying on the Farhy argument as a reason to leave Form 5471 unfiled is therefore relying on a defence that, even at its strongest, does nothing about the foreign tax credit reduction, nothing about section 6501(c)(8), and nothing about the section 6679 exposure that can sit alongside a section 6046 failure. This is a gap in the popular commentary that we think is worth stating plainly.

How section 6501(c)(8) keeps the whole year open

IRC section 6501(c)(8)(A) provides that where information required under section 6038 has not been furnished, the time for assessment of any tax with respect to any return, event or period to which that information relates does not expire before the date three years after the information is furnished. An unfiled Form 5471 therefore holds the assessment window open indefinitely, and only filing starts the three-year run.

IRC section 6501(c)(8)(B) narrows that considerably where the failure is due to reasonable cause and not willful neglect. In that case the extended period applies only to the item or items related to the failure, rather than to the whole return. For a client with a complex return, that distinction is worth as much as the penalty relief itself, because it is the difference between one item being open and every position on the return being open.

Worked scenario: a London-based owner catching up on three years

Marcus Halloran is a US citizen resident in London who owns 100 percent of Thornbury Partners Ltd, a UK consulting company. The company made roughly GBP 900,000 of taxable profit in its most recent completed year and paid UK corporation tax at the 25 percent main rate, so about GBP 225,000 of UK corporation tax. Marcus has consistently made a section 962 election on his Form 1040 so that his tested income inclusion is taxed at corporate rates with a deemed-paid credit for the company's UK tax. His US liability on the inclusion has been close to nil. He has never filed Form 5471 for the company, for any of the last three years.

Under section 6038(b)(1) the starting exposure is USD 10,000 for each annual accounting period, so USD 30,000 across three years, before any escalation and before reasonable cause is considered. Under section 6038(c)(1) the additional exposure for the most recent year is a 10 percent reduction of the UK corporation tax attached to that year, which is roughly GBP 22,500 of tax removed from the pool that supports his deemed-paid credit. The section 6038(c)(2) cap does not bind, because the company's income for the period comfortably exceeds the reduction. The section 6038(c)(3) coordination rule then reduces that credit cut by the USD 10,000 dollar penalty imposed for the same failure. The two earlier years produce their own parallel calculations on their own tax pools.

The practical effect is that the credit reduction converts what had been a nil US liability into a real one, because the deemed-paid credit no longer fully covers the tax on the inclusion, and interest runs on that liability from the original due date of each return. If the IRS mails a notice and Marcus takes another year to file, a further 5 percent comes off for each three-month period, and the position deteriorates quarter by quarter while the dollar penalty has already stopped growing at its ceiling. Filing is what ends it.

Does reasonable cause stop the section 6038(c) reduction?

Yes, and it is the same statutory hook that relieves the dollar penalty. IRC section 6038(c)(4)(B) treats the time periods that drive the reduction as extended where the failure is shown to be due to reasonable cause, so a successful showing prevents the reduction from ever starting to run for the period in question. Treasury Regulation section 1.6038-2(k) sets out the procedure: the person must make an affidavit setting out all the facts alleged as reasonable cause, filed under penalties of perjury with the IRS office where the return is required to be filed, and the IRS determines whether reasonable cause existed and for how long.

The standard is ordinary business care and prudence, judged on all the facts. In our preparation work the facts that carry weight are consistent and unglamorous ones: full and timely disclosure of the company to the preparer who filed the returns, complete UK statutory accounts and Companies House filings, UK corporation tax paid on time, no pattern of moving funds to obscure ownership, and prompt remediation once the gap was identified. The facts that undermine a claim are equally consistent: awareness of the requirement, written professional guidance that was not followed, or a filing gap that only ended after the IRS made contact.

Assemble the evidence before choosing a route. The reasonable cause narrative determines whether you file through the Streamlined Filing Compliance Procedures, through delinquent information return procedures, or by amending returns with a reasonable cause statement.
Do not treat the section 6038(c) reduction as automatic. Where reasonable cause is established for the period, the reduction does not run.
Recompute the credit position for every open year rather than only for the year in which the omission was noticed, because each annual accounting period is a separate failure with its own pool of tax.
Get the section 962 election documentation in order for every year in the catch-up, since that election is what puts the deemed-paid credit on the return in the first place.
File complete forms with every required schedule. A Form 5471 that is filed but not substantially complete is still a failure, and it restarts nothing.

What a US owner of a UK limited company should do now

If you are a US person holding 10 percent or more of a UK limited company, assume a Form 5471 obligation exists and that it sits with your Form 1040, due on the same date including extensions. The categories that usually apply to owner-managed UK companies are Category 3 for acquisitions and disposals of a 10 percent interest, Category 4 for control, and Category 5 for a US shareholder in a controlled foreign corporation. HMRC has no equivalent filing, and nothing in the UK compliance cycle will flag the gap for you, which is why these omissions run for years.

Where years are missing, the sequence matters. Establish the ownership history and the categories for each year. Rebuild the company's earnings and profits and its UK corporation tax by annual accounting period. Recompute the inclusions, including the transition from the GILTI regime to net CFC tested income for tax years beginning after 31 December 2025, and the credit position under any section 962 election. Only then quantify the section 6038(b) and section 6038(c) exposure with the section 6038(c)(2) cap and section 6038(c)(3) coordination applied. Choose the remediation route on the basis of that quantified position and the strength of the reasonable cause facts, and file everything together with the affidavit contemplated by the regulation.

We prepare Form 5471 catch-up filings for US owners of UK companies as a complete compliance exercise: the information returns, the recomputed inclusions and credits, the FBAR and Form 8938 positions that usually travel with them, and the reasonable cause documentation, filed as one coherent submission rather than as a sequence of unconnected forms. Doing it in that order is what stops the section 6038(c) clock and closes the section 6501(c)(8) window.