Introduction: The Itemized Deduction Limit Returns for 2026
The itemized deduction limit is back for the 2026 tax year, and it reduces the deductions of every American in the 37% bracket by 2/37. Congress suspended the old version for eight years. The law signed on 4 July 2025 replaced it with a new, permanent formula that applies to tax years beginning after 31 December 2025. Consequently, the 2026 return you file in 2027 is the first one it touches.
American commentary describes the rule as a 35% cap on the value of deductions. That shorthand is accurate for a salaried New Yorker. However, it misleads an American living in London. Your filing status is probably different, your income is mostly foreign and your UK tax usually creates surplus foreign tax credits. Therefore, the same itemized deduction limit can cost one American in Britain nothing and another several thousand dollars.
At TaxYork, we prepare US and UK tax returns for high-earning Americans in Britain, including investment bankers, partners, investors and company owners. This guide explains the formula, the 2026 thresholds, the stacking with the SALT cap, and the question no US guide answers: when does the cut cost an American in Britain actual cash?
How the Itemized Deduction Limit Works in 2026
The Itemized Deduction Limit Formula in Section 68
The rule sits in section 68 of the Internal Revenue Code. It reduces your itemized deductions by 2/37 of the lesser of two amounts. The first amount is your total itemized deductions. The second is the amount by which your taxable income, before those deductions, exceeds the point where the 37% bracket begins.
The itemized deduction limit therefore has an upper bound. It can never remove more than 2/37 of your deductions, which is about 5.4%. For a taxpayer deep inside the top bracket, a deduction that used to save 37 cents per dollar now saves 35 cents. That arithmetic is where the 35% label comes from.
The 2026 Thresholds by Filing Status
The itemized deduction limit only bites once you reach the 37% bracket. Revenue Procedure 2025-32 sets the 2026 starting points. The bracket begins at $640,600 of taxable income for a single filer or head of household. It begins at $768,700 for a married couple filing jointly. For a married person filing separately, it begins at $384,350.
That last figure matters most in Britain. Many Americans here are married to someone who is not a US citizen. Unless they make a special election, they file as married filing separately. As a result, the itemized deduction limit reaches them at half the income at which it reaches a couple in America.
Three Worked Positions
Consider a single filer with $50,000 of itemized deductions. In the first position, taxable income before deductions is $600,000. That figure sits below $640,600, so the itemized deduction limit does not apply at all.
In the second position, taxable income before deductions is $660,000. The excess over the threshold is $19,400, which is less than the $50,000 of deductions. The reduction is therefore 2/37 of $19,400, or $1,049. In the third position, income before deductions is $1,000,000. The excess far exceeds the deductions, so the reduction is 2/37 of $50,000, or $2,703. At 37%, that adds roughly $1,000 of tax.
How It Differs From the Old Pease Rule
Before 2018, the Pease limitation cut deductions by 3% of income above a threshold, up to 80% of the total. The new formula is gentler in size. However, it is wider in scope. The old law protected medical expenses, investment interest, casualty losses and gambling losses. The current text of section 68 contains no such list. Accordingly, every itemized deduction on Schedule A now takes the cut, including investment interest claimed on Form 4952.
Is Itemizing Still Worth It From Britain?
Many Americans in Britain never itemize, because council tax, UK charitable donations and UK income tax claimed as a credit produce no Schedule A deduction. For them the standard deduction wins, and section 68 is irrelevant. The question only arises once US-deductible mortgage interest, US state taxes, US charitable donations or investment interest exceed $16,100 for a separate filer or $32,200 for a couple.
The comparison has changed for 2026. Previously, you compared total itemized deductions with the standard deduction. Now you must compare the figure that survives the SALT cap, the charitable floor and the itemized deduction limit. A separate filer with $18,000 of deductions before those three tests may find that fewer than $16,100 survive. In that case the standard deduction is the better claim, and the calculation should be run both ways before the return is prepared.
Which Deductions the Cut Reaches for Americans in Britain
Mortgage Interest on a UK Home
Mortgage interest on your London home is deductible on a US return, even though HMRC gives no relief for it. The US rules limit the deduction to interest on $750,000 of acquisition debt, or $375,000 for a married person filing separately. IRS Publication 936 explains the calculation. For many Americans in Britain, this is the single deduction that makes itemizing worthwhile, and the itemized deduction limit now trims it. Our guide to the UK mortgage for US expat owners covers the wider reporting.
Sterling Deductions and the Exchange Rate
Mortgage interest paid in sterling must be translated into dollars before it reaches Schedule A. Most Americans in Britain use the IRS yearly average exchange rate for recurring payments. A weaker dollar therefore inflates both your sterling salary and your sterling deductions in dollar terms. As a result, a London employee whose pay has not changed can cross the $384,350 or $640,600 line through currency movement alone. The threshold test deserves a fresh check each year, using the rate for that year.
US State Taxes and the SALT Cap
Section 68 applies after every other limit. The SALT cap in section 164 therefore comes first. For 2026 the cap is $40,400, or $20,200 for a separate filer. However, it shrinks by 30% of modified adjusted gross income above $505,000, or $252,500 for a separate filer, until it reaches a floor of $10,000 or $5,000.
The arithmetic produces a result that few guides spell out. A single filer reaches the $10,000 floor at about $606,000 of income. A separate filer reaches the $5,000 floor at about $303,000. Both figures sit below the 37% bracket. In practice, therefore, almost anyone caught by the itemized deduction limit has already lost the higher SALT cap. Furthermore, UK council tax earns no deduction at all, as our article on the SALT cap and UK council tax explains.
Charitable Contributions and the New Floor
A second 2026 change stacks on top. Under section 170, charitable contributions are now deductible only to the extent they exceed 0.5% of adjusted gross income. The remaining deduction then meets the itemized deduction limit. Additionally, a donation to a UK charity generally earns no US deduction, while a donation to a US charity earns no Gift Aid. IRS Publication 526 sets out which organisations qualify.
UK Tax Deducted Instead of Credited
Most Americans in Britain credit their UK income tax against US tax. A few deduct it instead, usually in a year when the credit would be wasted. The SALT cap does not apply to foreign income taxes. However, the foreign tax deduction is an itemized deduction, so the itemized deduction limit now applies to it. Our analysis of deducting foreign tax instead of claiming the credit needs that adjustment for 2026 onwards.
What the Limit Does Not Touch
Several important items sit outside Schedule A, and the itemized deduction limit leaves them alone. The standard deduction is unaffected. For 2026 it is $16,100 for single and separate filers and $32,200 for joint filers. Similarly, the foreign earned income exclusion, the qualified business income deduction and pension contributions relieved under the US-UK tax treaty are not itemized deductions. Importantly, the foreign tax credit itself is a credit, not a deduction, so the formula never reduces it directly.
When the Itemized Deduction Limit Costs Real Cash
Surplus UK Credits Often Absorb the Cut
This is the point that separates an American in Britain from one in America. UK income tax reaches 45% above £125,140, as HMRC's income tax rates show. The top US rate is 37%. Consequently, a London salary normally generates more UK tax than the US charges on the same income, and the surplus becomes an unused foreign tax credit.
The itemized deduction limit raises your US taxable income. Where that extra income is foreign-source salary in the general category, your surplus UK credits cover the extra US tax. You pay nothing more. You simply use slightly more of a credit balance that would probably have expired. For a purely UK-salaried American, therefore, the itemized deduction limit is often invisible in cash terms.
US-Source Income Has No Such Shield
The position changes once you have US-source income. Dividends and interest from US investments, rent from US property, pay for US workdays and a share of US partnership profits all fall outside the reach of UK credits on the US return. Extra US tax on that income is real.
Moreover, the apportionment rules make matters worse. Under Treasury Regulation 1.861-8, charitable deductions are set against US-source income, and state taxes follow the income that bore them. Those are exactly the deductions that shelter US-source income. When the itemized deduction limit trims them, the extra tax lands where no UK credit can reach. IRS Publication 514 describes how deductions feed into the credit limitation on Form 1116.
A Large Capital Gain Can Trigger the Limit
The threshold test uses total taxable income. That figure includes long-term capital gains and qualified dividends, even though they are taxed at 20%. Therefore, an American with a modest salary can fall into the itemized deduction limit in the year they sell a company, a property or a large share position.
In that year the 35% label stops being accurate. Deductions reduce ordinary income first. The lost deductions are accordingly taxed at whatever ordinary rate your salary reaches, which may be 24%, 32% or 35%. The cost is smaller than the headline suggests, but it arrives in a year when many sellers have also made large charitable or investment interest claims.
The Foreign Earned Income Exclusion Changes the Test
Income excluded under the foreign earned income exclusion is not part of taxable income. For 2026 the exclusion is $132,900. On the wording of section 68, an American who claims it therefore reaches the 37% threshold later than one who relies on credits alone. However, the exclusion brings its own costs, including the loss of credits on the excluded income. The comparison belongs in the return preparation, and it should use real figures for both methods.
The Net Investment Income Tax
The 3.8% Net Investment Income Tax allows deductions that are properly allocable to investment income. The regulations apply the section 68 reduction to those deductions as well. Consequently, investment interest and state taxes on investment income may save slightly less against that tax from 2026. Foreign tax credits cannot offset it, so any increase is a cash cost. Our guide to the Net Investment Income Tax for dual filers covers the wider calculation.
Filing Status: The Lever Most Americans in Britain Overlook
Married Filing Separately at $384,350
An American married to a British spouse who has no US filing duty normally files separately. The 37% bracket then starts at $384,350. At an exchange rate of $1.30, that is a taxable income of roughly £296,000. Many directors, partners and senior bankers in London exceed it comfortably. Meanwhile, the same person's SALT cap is $5,000 and the mortgage debt limit is $375,000. Our guide to married filing separately for US-UK couples explains the status in full.
Head of Household at $640,600
Some Americans with a non-US spouse qualify as head of household, typically where a qualifying child lives with them. The IRS sets out the conditions in its guidance on a nonresident spouse. The 37% bracket for that status starts at $640,600, and the SALT and mortgage limits double. For a parent earning between $384,350 and $640,600, the correct status removes the itemized deduction limit altogether.
The Election to File Jointly
Alternatively, a couple can elect to treat the non-US spouse as a US resident and file jointly. The threshold then rises to $768,700. However, the election brings the spouse's worldwide income and foreign accounts into the US system, and it is hard to reverse. Our article on the section 6013(g) election for a British spouse sets out the consequences. The itemized deduction limit alone will rarely justify it, but it now belongs in the comparison.
The UK Side: Why HMRC Sees None of This
Two Systems That Restrict Relief Differently
The UK return is unaffected by section 68. HMRC restricts reliefs in its own way. It withdraws the personal allowance between £100,000 and £125,140 of income, which creates a 60% marginal rate. It also tapers the pension annual allowance for the highest earners. In contrast, it gives pension tax relief and Gift Aid relief at your full marginal rate, up to 45%.
What That Means for Timing
The two systems therefore reward different behaviour. A UK pension contribution still earns relief at 45% in Britain and, under the treaty, reduces US income without appearing on Schedule A. The itemized deduction limit does not reach it. On the other hand, mortgage interest earns nothing in Britain and slightly less than before in America. Sophisticated dual filers should accordingly rank their deductions by the combined result on both returns, not by the US saving alone.
What to Review Before 31 December 2026
The itemized deduction limit is an annual test, so timing matters. An American whose income moves above and below the 37% threshold from year to year benefits more from deductions claimed in the lower year. Bonus timing, the date of a share sale and the tax year in which a US charitable donation is paid all affect the result. Furthermore, a cash-basis taxpayer deducts mortgage interest and state taxes in the year of payment, which gives limited room to shift December and January payments. None of these steps changes your UK position, but each should be checked against the UK return before you act.
Estimated Tax and Payments on Account
A higher US liability can also affect quarterly estimated payments made with Form 1040-ES. Americans in Britain with US-source income should check their 2026 safe harbour figures now, because the first return under the itemized deduction limit will otherwise produce an underpayment charge. The UK payments on account run on a different calendar, and the two schedules need to be planned together.
Case Study: Two Americans in London, Two Different Results
The following examples are illustrative and use rounded figures. Rachel is a US citizen and a managing director at a London bank. Her husband is British and has no US filing duty, so she files separately. Her 2026 pay is $580,000, all for work in London. She pays $36,000 of deductible interest on her London mortgage, gives $30,000 to a US charity and pays $18,000 of property tax on a home she kept in Connecticut.
Start with the older limits. Her income exceeds the SALT phase-down range, so the property tax deduction falls from $18,000 to the $5,000 floor. The 0.5% floor removes $2,900 of the charitable deduction, leaving $27,100. Her itemized deductions before section 68 are therefore $68,100. Her income before deductions exceeds $384,350 by $195,650, which is more than her deductions. The reduction is accordingly 2/37 of $68,100, or $3,681, and she may deduct $64,419.
At 37%, the reduction adds $1,362 of US tax before credits. However, all of Rachel's income is UK salary taxed at up to 45%. Her surplus UK credits absorb the whole amount. The itemized deduction limit costs her no cash in 2026. It merely reduces a credit carryover she was unlikely to use.
Michael's position differs. He is a single US citizen and a partner in the London office of a US law firm. His taxable income before deductions is $1,400,000, and 30% of his profit share is US-source. He gives $120,000 to US charities, pays $37,500 of mortgage interest, pays $40,000 of investment interest and pays $55,000 of US state taxes on his partnership income.
The SALT floor cuts his state tax deduction to $10,000. The charitable floor of $7,000 leaves $113,000. His deductions before section 68 total $200,500. The reduction is 2/37 of that figure, or $10,838, which adds $4,010 of tax at 37%. Because his charitable and state tax deductions sit against US-source income, most of that $4,010 is cash that no UK credit offsets. Across the three limits, Michael loses $62,838 of deductions, worth $23,250 at his marginal rate. The itemized deduction limit is the smallest of the three, but it is the one his previous returns never showed.
How TaxYork Can Help
We prepare the US and UK returns together, so the deduction choices on one reflect the result on the other. For the 2026 year, our preparation process tests the standard deduction against itemizing after the itemized deduction limit and the two older caps, apportions the surviving deductions correctly on Form 1116 and confirms that your filing status is the most favourable one available to you.
Our US tax return preparation for Americans in Britain covers Schedule A, Form 1116 and Form 4952. In addition, our foreign tax credit and treaty relief work makes sure surplus UK credits are tracked and used. Clients with a mortgage, an investment account or a company on both sides of the Atlantic use our cross-border tax planning and compliance service. We also help clients with missed US tax returns bring earlier years up to date before the 2026 return is filed.
Professional bodies publish useful technical background. The AICPA tax resources, the ICAEW Tax Faculty and the Chartered Institute of Taxation all follow these changes, and IRS Publication 54 remains the starting point for Americans abroad.
Conclusion
The itemized deduction limit is a modest rule with an uneven effect. It removes at most 5.4% of your deductions, and only once your income reaches the 37% bracket. For an American in Britain on a UK salary, surplus UK credits usually absorb the extra US tax. However, the rule costs real cash where you have US-source income, a large capital gain or investment income subject to the 3.8% tax.
Therefore, the right response is measurement, not alarm. Check which filing status applies to you, because the threshold ranges from $384,350 to $768,700. Model the standard deduction against itemizing for 2026. Above all, look at where your deductions fall on Form 1116, because that decides whether the cut costs you anything at all.
Contact Us
If your income is near or above the 37% bracket, ask us to review your 2026 position before the year ends. You can book a consultation with our US-UK team, email hello@taxyork.com or call 020 3488 8606. We will prepare both returns and show you what the itemized deduction limit costs on your own figures.
Disclaimer
This article provides general information only and does not constitute tax, legal or financial guidance for your circumstances. Tax rules, thresholds and exchange rates change, and their application depends on your own facts. The case studies are illustrative. You should obtain professional help from a qualified US-UK tax specialist before acting on any information in this article. TaxYork accepts no liability for actions taken in reliance on this content.