Does a UK limited company paying 25 percent corporation tax automatically qualify for the GILTI high-tax exclusion?

No. The regulations test an effective rate of foreign tax computed on income measured under US federal income tax principles, not the UK statutory rate. Research and development relief, patent box treatment, capital allowances, losses brought forward and group relief can all reduce the UK tax actually paid or accrued and push the effective rate below the threshold in a given year. The calculation has to be run on real numbers annually and documented.

What is the effective foreign tax rate threshold for the GILTI high-tax exclusion?

Regulations section 1.951A-2(c)(7)(i) requires an effective rate of foreign tax greater than 90 percent of the maximum rate of tax specified in section 11. Because the section 11 corporate rate is 21 percent, that means an effective foreign rate above 18.9 percent, the figure Treasury and the IRS used in the preamble to the final regulations. The 2025 tax legislation did not change the section 11 rate, so the test still points to the same figure.

Who makes the GILTI high-tax exclusion election if I own 100 percent of my UK company?

You do, as the controlling domestic shareholder. Regulations section 1.964-1(c)(5) defines controlling domestic shareholders as the US shareholders who in aggregate own more than 50 percent of the total combined voting power, and a sole owner of a UK limited company satisfies that alone. The election is made by filing the statement required under Regulations section 1.964-1(c)(3)(ii) with a timely filed original federal income tax return. A sole shareholder is relieved from filing a separate statement where the information appears on the Form 5471 package, but filing it anyway is the defensible practice.

Where is the GILTI high-tax exclusion reported on Form 5471?

The excluded income comes out in the exclusions block of Schedule I-1, at the high-tax exception line, which reduces the tested income or tested loss reported at line 6. The related UK corporation tax is then not tested foreign income taxes at line 7. Schedule Q carries a high-tax election column so the position is visible on the return, and Schedules E, E-1, J and P still report foreign taxes, earnings and profits and previously taxed earnings. Form 8992 Schedule A picks up the resulting Schedule I-1 figures.

If I elect the high-tax exclusion, is my UK company's profit ever taxed again in the US?

Yes, when it is distributed. Excluded income does not become previously taxed earnings and profits, so it stays in the company's ordinary earnings and profits and a later distribution is a dividend. It will generally be a qualified dividend because the company is entitled to benefits under the US-UK income tax treaty, taxed at long-term capital gain rates plus the net investment income tax, and there is no UK withholding tax on the dividend to credit against it. That makes the election far stronger for a founder who retains profit than for one who distributes it every year.

GILTI High-Tax Exclusion for UK Companies

Q: Can I make the GILTI high-tax exclusion election for a prior year on an amended return?

Yes, but only within a fixed window. The election or a revocation may be made on an amended return filed within 24 months of the unextended due date of the original return for the US shareholder inclusion year with or within which the CFC inclusion year ends. Where there is more than one US shareholder, all required amended returns must be filed within a single period of no more than six months inside that window. After the window closes the only route is a request for relief through the private letter ruling process.

The GILTI high-tax exclusion is an annual election under Regulations section 1.951A-2(c)(7) that removes high-taxed income of a controlled foreign corporation from the tested income base entirely, and for a US citizen who owns a profitable UK limited company it is usually the difference between a current US charge on undistributed UK profits and no inclusion at all. UK corporation tax is high enough that most straightforward trading companies clear the regulatory rate test. Clearing the test is not the same as making a valid election. The election belongs to the controlling domestic shareholders, is made by filing a specific statement with a timely filed return, binds every US shareholder, must be applied consistently across a group of controlled foreign corporations, and runs straight through the Form 5471 package for years afterwards. This guide sets out the preparation and compliance mechanics.

One naming point first. The 2025 tax legislation renamed the section 951A inclusion: for tax years beginning after 31 December 2025 the statutory label is net CFC tested income, or NCTI. The same legislation cut the section 250 deduction from 50 percent to 40 percent, removed the deemed tangible income return that previously sheltered a routine return on qualified business asset investment, and reduced the section 960(d) haircut on deemed paid credits from 20 percent to 10 percent. The exclusion itself sits in section 954(b)(4) and the section 951A regulations and was not repealed. Because losing the tangible asset shelter leaves more tested income exposed, the election has become more valuable to a UK company owner, not less. The forms and practice still use the GILTI label, so both terms appear below.

What is the GILTI high-tax exclusion, and who can use it?

A US shareholder is a US person who owns 10 percent or more of the vote or value of a foreign corporation. A foreign corporation is a controlled foreign corporation, or CFC, when US shareholders together own more than 50 percent of its vote or value. A US founder who owns all of the shares in a UK limited company is therefore a US shareholder of a CFC, files Form 5471 as a Category 5 filer, and is exposed to a current inclusion on the company's tested income whether or not a single pound leaves the company's bank account.

The exclusion switches that off for income that has already borne a sufficiently high foreign tax. Regulations section 1.951A-2(c)(7)(i) provides that a tentative gross tested income item qualifies for the exception described in section 954(b)(4) only if the related tentative tested income item was subject to an effective rate of foreign tax greater than 90 percent of the maximum rate of tax specified in section 11. The section 11 corporate rate is 21 percent, so the test is an effective foreign rate above 18.9 percent, the figure Treasury and the IRS used in the preamble to the final regulations. Note the drafting: the threshold is a fraction of the section 11 rate rather than a fixed percentage, so it moves automatically if Congress changes the corporate rate. The 2025 legislation did not.

How is the effective foreign tax rate actually computed for a UK company?

This is where most UK company owners are given a wrong answer, because the test is not the UK statutory rate. Regulations section 1.951A-2(c)(7)(vi) computes the effective rate as the US dollar amount of foreign income taxes paid or accrued with respect to the tentative tested income item, divided by the US dollar amount of that item increased by those same taxes. The income in the denominator is measured under US federal income tax principles from the tested unit's separate books and records, with adjustments for disregarded payments. It is neither the profit in the accounts filed at Companies House nor the profit chargeable on the CT600.

That distinction matters because a UK company at the 25 percent main rate has only around six percentage points of headroom above the threshold, and several ordinary UK features consume it quickly.

Research and development relief and the research and development expenditure credit, which cut the UK tax bill in the numerator without a matching reduction to income measured for US purposes
Patent box treatment, which applies a lower effective UK rate to a slice of the trade
Capital allowances, including full expensing, where the UK deduction runs well ahead of the US depreciation deduction for the same asset
Losses brought forward and group relief surrendered from an associated company, both of which reduce UK tax accrued for the period
Permanent differences between the UK and US measures of profit, which move the denominator only
Timing, because the test looks to foreign income taxes paid or accrued, and UK corporation tax is normally payable nine months and one day after the period end, or by quarterly instalments for larger companies
Currency, because both tax and income are translated into US dollars and a sterling movement can shift the ratio either way

An R&D-intensive UK software or biotech company can therefore fail the rate test in a heavy claim year while its headline rate is still 25 percent. The test has to be run on real numbers every year and the working papers have to show the reconciliation. GOV.UK sets out the UK framework: a main rate of 25 percent on profits over 250,000 pounds, a small profits rate of 19 percent on profits of 50,000 pounds or less, and marginal relief in between, with both limits proportionately reduced for short accounting periods and divided by the number of associated companies. A founder who has incorporated three companies has quartered those limits, pulling more profit into the marginal band for reasons that have nothing to do with trading performance.

What is a tested unit, and does a UK limited company have more than one?

The final regulations abandoned a single company-wide test in favour of a tested unit approach. Under Regulations section 1.951A-2(c)(7)(iv), a tested unit is the CFC itself, an interest in a pass-through entity that is a tax resident of a foreign country or that is treated as non-transparent under the CFC's own local law, or a branch that gives rise to a taxable presence under the law of either the branch jurisdiction or the owner. A combination rule then treats tested units of the same CFC that are tax residents of, or located in, the same foreign country as a single tested unit, subject to an exception for certain non-taxed branches.

For most US founders in the UK the answer is that there is exactly one tested unit and the test is run once. A standalone UK limited company that trades only in the UK is the CFC and nothing else. Additional tested units appear in recognisable situations.

The UK company has a permanent establishment or registered branch in another country and is taxed there on that activity
The UK company holds a membership interest in an LLP or a foreign partnership that is a tax resident of, or located in, a jurisdiction outside the UK
The UK company owns a subsidiary elsewhere that has been checked open to disregarded status, so its activity folds into the UK company for US purposes but is taxed locally
The UK company owns a disregarded US limited liability company, which brings the disregarded payment adjustment rules into play

This matters because the rate test is applied unit by unit, not to the consolidated result. A well-taxed UK trade does not rescue a lightly taxed branch elsewhere: the branch is tested on its own, may fail, and its income then stays inside the tested income base while the UK unit's income comes out. A founder who assumes a single blended answer reports the wrong number on Schedule I-1.

Who makes the election, and exactly how is it made?

The election is not made by the company, nor by every shareholder individually. Regulations section 1.951A-2(c)(7)(viii)(A) provides that it is made by the controlling domestic shareholders, defined by cross-reference to Regulations section 1.964-1(c)(5) as the US shareholders who in the aggregate own more than 50 percent of the total combined voting power, in accordance with the rules provided in forms or instructions and by filing the statement required under Regulations section 1.964-1(c)(3)(ii) with a timely filed original federal income tax return. A sole US founder makes the election alone.

The statement is a specific document, not a note in the margin. Regulations section 1.964-1(c)(3)(ii) requires it to contain the following.

The name, country of organization and US employer identification number of the foreign corporation, where it has one
The name, address, stock interests and employer identification number of each controlling domestic shareholder
A description of the action taken on behalf of the foreign corporation and the taxable year for which it is made
Identification of a designated shareholder who retains a jointly executed consent confirming that the action has been approved by all of the controlling domestic shareholders
Filing with, and on or before the due date including extensions of, the shareholder's own federal income tax return

There is a trap in the same paragraph that is widely misread. Regulations section 1.964-1(c)(3)(ii) states that no separate statement need be filed where the controlling domestic shareholder is the sole shareholder of the controlled foreign corporation and the required information is included on the Form 5471 and other applicable forms filed with the return. That relief is often taken to mean a single founder need do nothing at all to elect. File the statement anyway. It costs one page, it dates and identifies the election unambiguously, it removes any later argument about whether the Form 5471 package in fact carried the information, and it gives the preparer a fixed checklist item that survives a change of adviser.

Where there are other US shareholders, the controlling domestic shareholders must give written notice of the election, on or before that same filing date, to each domestic shareholder known to own stock. This is not a courtesy. Regulations section 1.951A-2(c)(7)(viii)(D) provides that a high-tax election, or a revocation of one, is valid only if all of the requirements of the election paragraph are satisfied, including the notice requirement. A founder who has brought in a US co-investor at 20 percent and has never sent a notice has an election with a defect on its face.

Two further features follow. The election applies to each tentative gross tested income item of the CFC for the CFC inclusion year and is binding on all United States shareholders, so a minority US shareholder cannot opt out and file on a different basis. And where the CFC is a member of a CFC group, the election is made for all members or for none. A CFC group here is an affiliated group under section 1504(a), read without the exclusions in section 1504(b)(1) through (6) and substituting more than 50 percent for at least 80 percent. A founder holding a UK trading company and a second foreign company under common control cannot elect for one alone.

The election is annual. It is made for a CFC inclusion year with no lock-in period; the 60-month restriction in the proposed regulations was not carried into the final rules. That flexibility suits a UK company whose effective rate swings with R&D claims, but it also makes the analysis a recurring compliance task rather than a one-off decision in a file note.

Can the election be made for an earlier year on an amended return?

Yes, within a window that is tighter than most founders assume. The election, or a revocation, may be made on an amended federal income tax return duly filed within 24 months of the unextended due date of the original return for the US shareholder inclusion year with or within which the CFC inclusion year ends. Where there is more than one US shareholder, each shareholder required to file must do so within a single period of no more than six months inside that 24-month window. Coordination is the part that fails in practice: US shareholders spread across different preparers rarely amend in step without someone driving the calendar.

The final regulations apply to taxable years of foreign corporations beginning on or after 23 July 2020, and to the years of US shareholders in which or with which those years end, with an option to apply them to years beginning after 31 December 2017 and before 23 July 2020 provided that is done consistently. Once the 24-month window closes, the remaining route is a request for an extension of time under the section 301.9100 relief regulations through the private letter ruling process. The IRS has granted that relief where a preparer omitted the election statement from an otherwise complete filing, and those rulings are published on IRS.gov, but it is a slow and expensive way to recover a missing page.

Where does the GILTI high-tax exclusion appear on the Form 5471 package?

The election statement is one page. Its consequences run through several schedules, and an inconsistency between them is the fastest way to draw an examiner's attention. Schedule I-1 of Form 5471, which reports the information used to compute the shareholder's inclusion, is the centre of gravity.

Line 1 reports the CFC's gross income in functional currency
Lines 2a through 2e report the exclusions: effectively connected income, subpart F income, income excluded by reason of the high-tax exception, dividends received from a related person, and foreign oil and gas extraction income
Line 3 totals the exclusions and line 4 is gross income less exclusions
Line 5 reports the deductions properly allocable to the amount on line 4, and line 6 is the tested income or tested loss that results
Line 7 reports tested foreign income taxes, which is zero where there is a tested loss
Line 8 reports qualified business asset investment, and lines 9a to 9d and 10a to 10c report tested interest expense and tested interest income

When the exclusion applies, the excluded amount is stripped out in the exclusions block and line 6 falls to zero, or to whatever remains from a unit or item that failed the rate test. Line 7 must follow the same logic: UK corporation tax attributable to excluded income is not tested foreign income taxes, because the income it relates to is no longer tested income. Schedule Q, which reports income by income group, carries a high-tax election column so the position is visible on the face of the return. Schedules E and E-1 still report foreign taxes and their movement, Schedule J still tracks earnings and profits, and Schedule P still tracks previously taxed earnings and profits by shareholder. Electing does not reduce the disclosure; it changes what the disclosure says.

Form 8992 is the shareholder-level computation. Its Schedule A pulls the pro rata share of each CFC's Schedule I-1 line 6 tested income or loss, line 8, line 9c, line 9d and line 10c. If the exclusion has taken line 6 to zero there is nothing to carry across, which is precisely the point. The filing duty does not change. A Category 5 filer still completes the full schedule set, and section 6038 imposes a 10,000 US dollar penalty for each annual accounting period of each foreign corporation where the required information is not furnished in time. That penalty applies whether or not any tax was due, which is exactly the position a successful exclusion creates.

When is the GILTI high-tax exclusion worth electing?

The election is close to costless for some founders and expensive for others. The variable that decides it is not the UK rate. It is what the founder does with the profit.

Elect where the UK company retains profit to fund working capital, hiring, product development or an acquisition, because nothing enters the US base at all
Elect where you do not want the annual administration of a section 962 election, with its own statement, computation and previously taxed earnings tracking
Elect where the effective rate clears the threshold with real headroom after R&D relief, patent box and capital allowances
Elect where the UK company is your only controlled foreign corporation, or where every member of the CFC group clears the test
Think again where you distribute substantially all profits every year, because the exclusion converts a sheltered inclusion into a plain dividend later
Think again where you also hold a lightly taxed foreign company whose inclusion is currently absorbed by credits generated by the UK company's tax
Think again where the effective rate sits within a point or two of the threshold, because one audit adjustment can invalidate the year

A worked scenario: a US founder with a profitable UK limited company

Take a US citizen resident in London who owns all of the shares in a UK limited company with 800,000 pounds of taxable profit for the year. The company is above the 250,000 pound upper limit so the main rate applies, giving a UK corporation tax charge of 200,000 pounds and 600,000 pounds of post-tax profit. The effective foreign rate, computed on US-measured income, comes out just under 25 percent after allowing for a modest timing difference on capital allowances. That is comfortably above the threshold, so the income qualifies and the founder may elect.

Case one, the founder retains the profit to fund a hiring plan. Electing removes the tested income entirely: no inclusion, no Form 8992 computation to speak of, no section 962 election, and the total tax on the year's trading profit is the UK corporation tax and nothing more. Without the election, and without a section 962 election, the founder would report an inclusion taxed at individual rates with no credit at all for the company's UK corporation tax, because an individual cannot claim deemed paid credits under section 960 unless a section 962 election is in place. The exclusion is decisively right here, and the compliance work is a rate computation, a statement and a correct Schedule I-1.

Case two, the founder distributes the entire 600,000 pounds as a dividend. The exclusion still removes the inclusion, but excluded income never becomes previously taxed earnings and profits. It stays in ordinary earnings and profits, so the distribution is a dividend for US purposes, generally a qualified dividend because the company is entitled to benefits under the comprehensive US-UK income tax treaty, taxed at long-term capital gain rates plus the net investment income tax. The UK imposes no withholding tax on dividends paid to a non-resident, so there is no fresh foreign tax to credit against it, and the UK corporation tax the company paid produces nothing in the US system because the income it related to left the tested income machinery before any credit mechanism could touch it. By contrast, an inclusion with a section 962 election brings the UK corporation tax in as a deemed paid credit and creates a previously taxed earnings account. Neither route is free for a founder who distributes everything, but the exclusion is the one that permanently strands the UK tax.

Case three, the same founder also owns a second foreign company in a low-tax jurisdiction inside the same CFC group. Without the election, the UK company's high tested foreign income taxes sit at shareholder level alongside the group's tested income in a single credit category and absorb much of the US tax attributable to the lightly taxed company. Elect, and both the UK income and the UK taxes leave that computation. The lightly taxed company fails the rate test on its own numbers, so its income stays in, now fully exposed with no blended credits behind it, and the all-or-nothing CFC group rule prevents electing for the UK company alone. This is the case where the exclusion destroys credits that were doing real work, and it is invisible unless both companies are modelled together before the return is signed. Credits in the section 951A category cannot be carried back or forward under section 904(c), so a credit wasted in the year is wasted permanently.

How does the election interact with the section 962 election and foreign tax credits?

The two elections answer different questions and pull in opposite directions for the same income. A section 962 election accepts the inclusion and changes how it is taxed, allowing an individual to be taxed at the corporate rate, to claim the section 250 deduction and to claim deemed paid credits for the company's foreign taxes, subject to the section 960(d) haircut. The high-tax exclusion refuses the inclusion, and with it the credits. Once income is excluded its foreign taxes are not tested foreign income taxes, they do not appear on Schedule I-1 line 7, they never enter the section 904 limitation and they cannot shelter anything else. For a founder with a single UK company that retains earnings that is a good trade, because there was no US tax to shelter in the first place. For a founder with a mixed group, or with other foreign-source income and a credit position to manage, it has to be modelled year by year, and the annual, revocable nature of the exclusion is what makes that modelling worth doing.

What records must a UK company owner keep to support the election?

An election supported by nothing more than a statement is an election waiting to be unwound. The regulations test an effective rate computed on income determined under federal income tax principles from separate books and records, so the file has to be able to reproduce that number years later.

The statutory accounts and trial balance for each period, with the mapping used to restate UK-measured profit onto US federal income tax principles
The CT600 and computation, the R&D or patent box claim schedules, capital allowance schedules and any group relief claim or surrender, since each moves the numerator
The tested unit analysis for the year, documenting any branch, pass-through interest or disregarded entity that creates a second unit
Evidence of foreign income taxes paid or accrued, including the payment date or instalment schedule and any later amendment to the UK liability
The currency translation workings converting both income and tax into US dollars, with the rates and conventions used
A signed copy of the election statement as filed, the return it was attached to, and, where there is more than one US shareholder, the jointly executed consent and dated proof of notice

One point only appears with hindsight. An HMRC enquiry that later adjusts the UK corporation tax liability for a period changes the numerator of the effective rate test for that same period. A founder who elected on a rate of, say, 19.4 percent and then loses part of an R&D claim may find the year no longer qualifies, with a US amendment following the UK settlement. The file should record the headroom that existed at the time, so the sensitivity is understood before an enquiry opens rather than after it closes.

The GILTI high-tax exclusion is one of the few elections available to a US founder in the UK that can take a large recurring US charge to zero, and for a company that reinvests its profits it usually should be made. It is also an election with a strict form, a hard deadline, a validity condition attached to a notice most founders have never heard of, and a footprint across the whole Form 5471 package. The compliance work is the election. Treat the rate computation, the statement, the tested unit analysis and the schedule mapping as one annual exercise and the position holds.