Form 1118 & US UK Tax Returns Preparation: UK Branches

Form 1118 is how a US C corporation claims a credit for UK corporation tax against its US federal tax. It is the corporate counterpart to Form 1116, but it is not a bigger version of the same form: it runs a separate section 904 limitation for each income category, pulls in deemed-paid credits under sections 960 and 78, and demands schedule-level expense apportionment.

For US groups with a London office, a UK branch, or a UK subsidiary, this single form decides whether 25% UK corporation tax genuinely reduces the US bill or is simply lost. Getting it right is the technical core of US UK tax returns preparation at corporate level, and it is where Jungle Tax most often finds credits stranded, baskets misallocated, and prior-year returns worth reopening.

What Form 1118 actually does

Form 1118, Foreign Tax Credit — Corporations, computes the credit a domestic corporation may take under sections 901 and 960 for income taxes paid, accrued, or deemed paid to a foreign government. It is filed with Form 1120 by the corporation's due date, including extensions. The IRS publishes the current version and its instructions at About Form 1118, with the detailed schedule-by-schedule guidance in the Instructions for Form 1118.

Three points separate it from the individual regime on Form 1116. First, a C corporation cannot use the simplified election available to individuals with small amounts of foreign tax — there is no de minimis escape hatch. Second, the corporate form carries deemed-paid credit machinery (Schedules C, D and E) that has no individual equivalent, because it must push controlled foreign corporation taxes up to the US shareholder. Third, the expense apportionment on Schedule H is not optional housekeeping: it directly shrinks the numerator of your limitation fraction and is the single most common reason a US group with profitable UK operations still cannot use its UK tax.

Who has to file it?

• Any domestic corporation electing the foreign tax credit under section 901 for the year.
• US corporations with a UK branch or permanent establishment paying UK corporation tax directly.
• US parents with a UK subsidiary generating a subpart F or net CFC tested income inclusion carrying deemed-paid taxes under section 960.
• Corporations receiving distributions of previously taxed earnings and profits (PTEP) that carry foreign withholding or income tax.
• Corporations that must report separate limitation loss, overall foreign loss or overall domestic loss account movements, or a foreign tax redetermination — these require Form 1118 even where no current credit is claimed.

S corporations, partnerships and LLCs taxed as partnerships do not file Form 1118. The credit passes through and the owners claim it on Form 1116 or on their own Form 1118 if they are corporate partners. A UK-incorporated company with no US filing obligation of its own never files Form 1118 — it claims UK double taxation relief on its CT600 instead.

Why the separate limitation categories decide the outcome

Section 904 caps the credit at the US tax attributable to foreign source taxable income. Critically, the cap is applied separately to each category, so excess UK tax in one basket cannot shelter US tax on income in another. A US corporation with a UK branch and UK-source royalties may need two complete Forms 1118, each with its own limitation fraction.

The categories currently in play are the section 951A category (net CFC tested income, previously GILTI), foreign branch category income, passive category income, general category income, section 901(j) income from sanctioned countries, and income resourced by treaty. The last of these matters more than most commentary allows: Article 24 of the US–UK double taxation convention can resource certain US-source income as UK-source for credit purposes, and each treaty resourcing is a separate limitation of its own.

Which basket does UK tax land in?

UK operating structure	Who pays UK corporation tax	Form 1118 category	Credit mechanism
UK branch / permanent establishment of the US corporation	The US corporation, via a UK CT600	Foreign branch category	Section 901 direct credit
UK subsidiary, tested income included as NCTI	The UK company	Section 951A category	Section 960(d) deemed paid, subject to the statutory haircut
UK subsidiary, subpart F income	The UK company	General or passive, by character	Section 960(a) deemed paid, no haircut
UK subsidiary paying a dividend out of non-PTEP earnings	The UK company	Generally none available	Section 245A dividends received deduction; section 245A(d) denies the credit
UK-source royalties or interest received by the US corporation	Withheld at source, if any	General or passive, by character	Section 901 direct credit
PTEP distribution from a UK subsidiary	The UK company historically	Category of the original inclusion	Section 960(b), reported on Schedule E

The UK trap generalist advisers miss

The instinct that "we paid 25% in the UK, so we credit 25% in the US" fails in the most common structure of all: a profitable UK subsidiary distributing dividends to a US parent.

Section 245A gives a US corporate shareholder a 100% deduction for the foreign-source portion of a dividend from a specified 10%-owned foreign corporation. Section 245A(d) then denies any credit or deduction for foreign taxes attributable to that exempt dividend. The UK corporation tax paid on those earnings is not creditable, is not deductible, and never appears on Form 1118 at all. The income is simply exempt on the US side and the UK tax is economically final.

The position is compounded by the high-tax exclusion. Tested income subject to an effective foreign rate above 90% of the US corporate rate — broadly 18.9% against a 21% federal rate — can be excluded from the tested income calculation by election. The UK main rate of corporation tax at 25% comfortably clears that threshold for most trading subsidiaries. Elect the exclusion and there is no NCTI inclusion, no section 960(d) deemed-paid credit, and no Form 1118 entry for that UK tax. Groups that assume UK tax is "banked" as a credit and can be used against other foreign income are frequently wrong; the correct analysis often produces no usable credit whatsoever, which changes the branch-versus-subsidiary decision materially. Our cross-border tax planning team models this before a UK entity is incorporated, not after.

Does a UK branch produce a better answer?

Frequently, yes. A UK permanent establishment pays UK corporation tax under HMRC's rules for non-resident companies trading through a PE, and that tax is paid by the US corporation itself. It is therefore a direct section 901 credit in the foreign branch category, available immediately against US tax on the same profits, with no dividend, no section 245A exemption and no high-tax election to navigate. HMRC's treatment of credit relief in the corporation tax context is set out in its International Manual.

The branch route carries its own costs: the group must file a UK corporation tax return for the PE, attribute profits under Article 7 of the treaty and UK transfer pricing rules, file Form 8858 with Schedule M on the US side, and confront the dual consolidated loss regime. It is a genuine trade-off, not a default.

The schedules, in the order they actually bite

• Schedule A — foreign source income and loss by category and by country. This is where UK branch profits, translated into US dollars, first appear.
• Schedule B — the credit computation itself: taxes paid, accrued and deemed paid, then the section 904 limitation.
• Schedule C — taxes deemed paid on subpart F inclusions under section 960(a).
• Schedule D — taxes deemed paid on section 951A / NCTI inclusions under section 960(d).
• Schedule E — taxes deemed paid on PTEP distributions under section 960(b). The December 2025 revision expanded this schedule to track section 951A PTEP distribution taxes separately.
• Schedule G — statutory reductions to the taxes otherwise credited, including the section 6038 information-return penalty reduction and the new section 960(d)(4) disallowance.
• Schedule H — apportionment of interest, research and experimental, stewardship and other deductions across categories.
• Schedule I — reductions for foreign oil and gas taxes.
• Schedule J — separate limitation loss, overall foreign loss and overall domestic loss accounts, and their recharacterisation.
• Schedule K — reconciliation of prior-year and current-year carryovers.
• Schedule L — foreign tax redeterminations affecting prior years.

Schedule H is where UK credits go to die

Interest expense is apportioned across categories on an asset basis, research and experimental expenditure by gross receipts, and stewardship expense to the dividends and inclusions it relates to. Each dollar apportioned to the foreign branch category reduces foreign source taxable income in that basket, shrinks the section 904 limitation, and converts creditable UK tax into an excess credit carryover. A US parent with heavy domestic borrowing and a modest UK branch can find that apportioned interest wipes out most of the branch limitation even though the UK operation is profitable on its own accounts. The fix is structural and must be planned before the year end, not discovered at filing.

What changed for 2026 — and why it matters for UK operations

The 2025 legislation reshaped the corporate credit for tax years beginning after 31 December 2025. Four changes have direct UK consequences.

• The NCTI haircut fell from 20% to 10%. Ninety per cent of foreign taxes deemed paid on net CFC tested income are now creditable, rather than eighty. For a UK subsidiary that does not use the high-tax exclusion, this is a meaningful improvement in credit yield.
• Expense apportionment to the NCTI basket was narrowed. Broadly, only directly allocable deductions and the section 250 deduction are apportioned to that category, so domestic interest and R&E no longer strand credits there. The relief does not extend to the foreign branch category, which is precisely where UK branch tax sits.
• A new sourcing rule for US-produced inventory sold through a foreign branch. Where a US corporation sells US-manufactured inventory for use outside the United States through a fixed place of business abroad, a portion of that income attributable to the foreign office may be treated as foreign source, capped at 50% of the income from the sale. For a US manufacturer selling into Europe through a London sales branch, this can rescue a foreign branch limitation that was previously nil.
• Section 960(d)(4) disallows a credit for 10% of foreign taxes on certain distributions of section 951A previously taxed earnings, reported at Schedule G.

The UK-side change nobody has connected to Form 1118

Diverted Profits Tax was repealed for accounting periods beginning on or after 1 January 2026 and replaced by the unassessed transfer pricing profits rules, which sit inside the corporation tax regime rather than alongside it. HMRC's guidance confirms the change of character: DPT was a separate and distinct tax outside the double taxation treaties, whereas the replacement is part of corporation tax and therefore a covered tax under UK treaties (see HMRC International Manual INTM489310).

The practical consequence for a US group is significant. A DPT charge was, on any reasonable analysis, difficult to credit on Form 1118 because it was not an income tax within the meaning of section 901 and sat outside the treaty. A charge arising under the replacement rules is corporation tax, imposed within a covered tax, and should follow the ordinary creditability analysis. Groups that historically treated a UK diverted profits exposure as pure economic cost should revisit that assumption for periods from 2026 onwards.

Two other UK levies do not improve. The UK Digital Services Tax is charged on revenues rather than net income and is not a creditable income tax; nor is it deductible against US tax as an income tax, though it may be deductible as a business expense. Pillar Two top-up taxes under the UK's multinational and domestic top-up tax rules remain in an unsettled creditability position, and the international position on how US-parented groups are treated has continued to evolve. Treat any assumption that a UK top-up tax is creditable as a position requiring documented support, not a default entry on Schedule B.

Carrybacks, carryforwards and the value of an unused credit

Excess credits in a category carry back one year and forward ten years, within the same category. The section 951A / NCTI category is the exception: excess credits there do not carry over at all, which is why a UK subsidiary with a mismatched inclusion year can lose credit permanently.

The credit is an annual, all-or-nothing election against the alternative of deducting foreign taxes under section 164. A corporation in a US loss position, unable to use credits and facing expiry, may find the deduction produces more value by increasing a net operating loss. That election can generally be changed within the extended refund window for foreign tax credits — a period considerably longer than the ordinary three-year statute, which is one of the most useful and least used facts in corporate international tax.

What a missed or incomplete Form 1118 costs

• Direct cash cost. Failing to file Form 1118 does not attract a standalone penalty; it simply means paying US tax on income that has already borne 25% UK corporation tax. On a UK branch generating £2m of profit, the cost of an unclaimed credit runs well into six figures per year.
• The section 6038 credit reduction. Failure to file the related information returns — Form 5471 for a UK subsidiary, Form 8858 for a UK branch or disregarded entity — reduces the foreign taxes available for credit by 10%, with a further 5% for each three-month period after a 90-day IRS notice period expires. The penalty attacks the credit itself, not just the wallet, and is reported on Schedule G.
• Fixed information-return penalties of $10,000 per form per year for late or incomplete Forms 5471 and 8858, with continuation penalties on notice.
• An open statute. Omitting a required international information return can keep the entire corporate return open beyond the normal three-year assessment period until the missing information is furnished.
• Redetermination penalties. Where UK tax changes after filing — a closure notice ending an HMRC enquiry, an amended CT600, a transfer pricing adjustment, or a refund of overpaid UK tax — section 905(c) requires notification to the IRS and, generally, an amended return with Schedule L. Failure to notify carries its own penalty regime.

The last point is the one that catches well-advised groups. HMRC enquiries routinely close two or three years after the UK return was filed. By then the US Form 1118 for that year has been signed, filed and forgotten, and nobody in the US tax function is watching the UK closure notice. A disciplined US and UK tax accountants relationship treats every HMRC adjustment as a US filing event.

Practical mechanics that go wrong

Currency and timing

A UK branch is a qualified business unit with sterling as its functional currency. Its profits are translated into US dollars, and the UK corporation tax is translated under the rules for accrued foreign taxes — generally at an average rate for the year of accrual, with adjustments where tax is paid more than two years after the close of the year. An accrual-basis corporation credits UK tax for the year to which it relates, not the year it is paid. UK corporation tax for a company outside the quarterly instalment regime is due nine months and one day after the accounting period ends, so the payment almost always falls in a later US tax year. Crediting on the cash date is a classic and expensive error.

Mismatched accounting periods

Where the UK entity has a 31 March or 31 December period end and the US group has a different fiscal year, the branch profit and the UK tax must be aligned to the US year. Where the UK company is a CFC, the inclusion year is determined by the CFC's own tax year ending with or within the US shareholder's year. Groups that simply lift the UK statutory accounts figures into Schedule A without this alignment are misstating both the numerator and the tax.

Dual consolidated losses

A UK branch is a separate unit for dual consolidated loss purposes. Its losses cannot offset US domestic income unless a domestic use election and agreement are made, and any subsequent foreign use — most obviously UK group relief surrendering the PE's losses to a UK affiliate — can trigger recapture with an interest charge. This is a genuine and frequently missed interaction between UK group relief planning and the US return.

Loss accounts and recapture

An early-stage UK branch that loses money creates a separate limitation loss or an overall foreign loss, tracked on Schedule J. When the branch turns profitable, that account recharacterises foreign source income as US source, shrinking the very limitation you need to use UK tax against. Groups launching UK operations should model the recapture profile at the outset rather than discovering in year four that the credit they expected is unusable.

A worked sequence for a US corporation with a UK branch

1. Prepare the UK PE accounts and CT600, attributing profits under Article 7 and UK transfer pricing rules; settle the UK corporation tax liability.
2. Translate branch income and UK tax to US dollars on the correct convention, matching the year of accrual.
3. Complete Form 8858 and Schedule M for the branch, on time, to protect the credit from the section 6038 reduction.
4. Populate Schedule A of the foreign branch category Form 1118 with foreign source income by country.
5. Apply Schedule H apportionment of interest, R&E and stewardship expense to that category, honestly and with contemporaneous support.
6. Test whether any US-produced inventory sold through the branch qualifies for the new partial foreign-source treatment.
7. Run the section 904 limitation on Schedule B and identify excess credit or excess limitation.
8. Update Schedule J loss accounts and Schedule K carryovers, and check whether a one-year carryback claim is worth filing.
9. Diary the HMRC enquiry window and any expected adjustment for a section 905(c) redetermination.

Fixing prior years

Most of the work we see is remedial: a US group that filed Form 1120 for several years without Form 1118, or with a single general category form covering income that belonged in three baskets, or with UK subsidiary tax credited that section 245A(d) plainly denied. The good news is that the refund window for claims attributable to foreign taxes is materially longer than the ordinary limitation period, so a properly documented reconstruction can often recover credit for years that would otherwise be closed.

Where information returns were also missed, the sequencing matters. Filing amended returns claiming credits while Forms 5471 or 8858 remain outstanding invites the section 6038 reduction against the very credits being claimed. The correct order is to remediate the information returns first, on a reasonable-cause basis where available, then claim. Our US tax services and UK tax services teams run both sides of that sequence together, and our private client practice handles the individual shareholder consequences that usually surface alongside.

US and UK relief compared

Feature	United States (Form 1118)	United Kingdom (CT600 double taxation relief)
Relief mechanism	Credit under sections 901 / 960, or deduction under section 164	Credit relief, or deduction of foreign tax from profits
Limitation basis	Separate section 904 limitation per income category	Source-by-source; credit limited to UK tax on that income
Excess relief	Carry back one year, forward ten, within category	Carry forward against future income of the same source; limited carry back
Branch profits	Foreign branch category, direct credit	Branch exemption election available to UK companies with overseas PEs
Dividends from subsidiaries	Generally exempt under section 245A; credit denied under 245A(d)	Most dividends exempt from UK corporation tax under the distribution exemption
Withholding tax on outbound dividends	Treaty rates apply to US-source dividends	No UK withholding tax on dividends under domestic law
Later adjustments	Section 905(c) redetermination and Schedule L	Amended return or enquiry closure notice adjustment

The questions worth asking before year end

• Is our UK presence a branch or a subsidiary, and does the credit outcome support that choice?
• If we run a UK subsidiary, have we modelled the high-tax exclusion at the 25% UK rate, and do we understand that electing it forfeits the deemed-paid credit?
• How much US interest and R&E expense is being apportioned to our foreign branch category, and can that be reduced legitimately?
• Are Forms 5471 and 8858 filed complete and on time for every UK entity and branch?
• Do we have a process that routes HMRC enquiry outcomes to the US tax function?
• Are there prior years where UK tax was paid and no US credit was claimed?

Form 1118 rewards preparation and punishes assumption. The categories, the apportionment and the deemed-paid rules interact in ways that generalist US corporate compliance rarely reaches, and the UK side — the 25% main rate, the repeal of Diverted Profits Tax, group relief, HMRC enquiry timing — changes the answer again. If your group has UK operations and you are not confident the UK tax you are paying is genuinely reducing your US bill, that is a question worth resolving before the next filing rather than after it. You can review our wider library of cross-border guides, or contact our cross-border team for a confidential, no-obligation review of your Form 1118 position, your prior-year exposure, and the credits that may still be recoverable.