Introduction: Expat Tax Connecticut Planning for British Families in Greenwich
The expat tax Connecticut position catches more wealthy British families off guard than any other state we cover, because Connecticut gives no credit for tax paid to the United Kingdom. Federal law softens double taxation through the foreign tax credit. Connecticut, however, only credits tax paid to other American states. Consequently, every pound of UK rent, every UK pension payment and every UK property gain can be taxed in Britain, taxed federally, and then taxed again in Hartford at up to 6.99%.
At TaxYork, we prepare federal and state returns for British portfolio managers, private equity partners, family office principals, company owners and retirees across Greenwich, Stamford, Darien, New Canaan and Westport. In our experience, the families who arrive from London assume the US-UK treaty protects them at every level. It does not. The treaty binds the federal government, not the states. Therefore the expat tax Connecticut question is not simply what rate you pay. It is which of your British income streams Connecticut will tax in full, with nothing to offset.
Expat Tax Connecticut Basics: Three Tax Systems, One Missing Bridge
A British household in Fairfield County deals with three income tax systems. First, federal tax reaches your worldwide income, relieved by the credit claimed on IRS Form 1116. Second, HMRC keeps taxing UK property income, UK land gains and any UK workdays. Third, Connecticut taxes its residents on the same worldwide income that reaches their federal adjusted gross income. The bridge between the first two is the treaty. Between Connecticut and Britain, however, there is no bridge at all.
Who This Guide Is Written For
This guide addresses high-net-worth British nationals, dual national US UK families and accidental Americans living in Connecticut. Specifically, it suits hedge fund and private equity professionals, investment bankers who commute to Manhattan, founders running companies from Greenwich, and retirees drawing UK pensions. If you still own London property, a SIPP, an ISA or a UK company, the expat tax Connecticut rules below decide how much of that wealth reaches you intact.
How Connecticut Compares With Our Other City Guides
Connecticut sits in the middle of the range. Boston adds a 4% surtax on income above roughly $1 million, and Philadelphia stacks a city wage tax on a low state rate. Meanwhile, Miami charges no state income tax at all. Connecticut's top rate looks moderate at 6.99%. Nevertheless, the absence of any foreign credit makes it far more expensive than the headline suggests for anyone with British income. For the wider federal picture, start with our complete guide to UK expat tax in the USA.
How Connecticut Taxes High Earners in 2026
Connecticut uses seven brackets, from 2% to 6.99%. For wealthy households, however, the brackets barely matter, because two clawback mechanisms convert the whole schedule into something close to a flat tax.
The 2025 Rate Schedule
The Connecticut Form CT-1040 instructions set the joint schedule at 2% on the first $20,000, rising through 4.5%, 5.5%, 6%, 6.5% and 6.9%, to 6.99% above $1,000,000. For single filers, the top rate starts at $500,000. Notably, the 2% bottom rate is recent: Connecticut cut it from 3% from the 2024 tax year. For 2026, the same structure applies, so your expat tax Connecticut planning can rely on these figures.
The 2% Phase-Out and the Benefit Recapture
Here is the mechanism most competitor guides skip. Connecticut first adds back the benefit of the 2% bracket once income passes $145,500 for joint filers, up to $500. Then it applies a "tax recapture" that claws back the lower brackets altogether. For joint filers, the recapture reaches its maximum of $6,800 at $1,080,000 of Connecticut AGI. For single filers, it reaches $3,400 at $540,000. Consequently, a couple with $1.4 million of income pays $97,760, which is within $100 of a flat 6.99% on every dollar.
What This Means for Your UK Income
The practical point is stark. Because the recapture flattens the schedule, every extra dollar of UK rent, UK dividends or UK gains costs a high earner 6.99% in Connecticut tax. There is no lower bracket to absorb it. Furthermore, Connecticut applies no preferential rate to capital gains, so a gain on a London flat costs the same 6.99% as salary. Therefore the expat tax Connecticut cost of British income is simple to estimate: multiply it by 6.99%, then ask whether anything offsets it.
No Local Income Tax, but High Property Tax
Connecticut towns levy no local income tax, unlike Philadelphia or Portland. Instead, they fund services through property tax, set as a mill rate per town. Greenwich has historically set one of the lowest mill rates in the state, whereas many neighbouring towns charge considerably more. Accordingly, where you buy within Fairfield County affects your annual cost as much as the income tax does. The Tax Foundation's Connecticut profile describes the state's income tax as one of the most complex in the country, largely because of the recapture.
Why Connecticut Gives No Credit for UK Tax
This section explains the core of the expat tax Connecticut problem, and it is the point that no ranking page addresses for British readers.
The Qualifying Jurisdiction Rule
Connecticut residents claim relief for tax paid elsewhere on Schedule 2 of Form CT-1040. However, the credit only covers a "qualifying jurisdiction", which the Department of Revenue Services defines as another US state, a local government within another state, or the District of Columbia. The instructions state plainly that a qualifying jurisdiction does not include "a foreign country or its provinces". Consequently, income tax paid to HMRC earns nothing in Connecticut, however much of it you pay.
The Treaty Does Not Help at State Level
The US-UK income tax treaty covers federal income taxes. Its relief article obliges the United States to credit UK tax, and the IRS honours that through Form 1116. Connecticut, however, is not a party to the treaty and has not adopted its relief provisions. Therefore the careful treaty analysis that fixes your federal return does nothing for your expat tax Connecticut bill. We see this misunderstanding in almost every new client file.
Why the Federal Credit Does Not Flow Through
Connecticut starts from federal adjusted gross income. The foreign tax credit, however, reduces federal tax, not federal income, so it never reaches the Connecticut computation. Similarly, deducting UK tax as an itemised deduction instead of crediting it does not help, because Connecticut starts from AGI rather than taxable income. In other words, the one federal relief that matters most for British income has no Connecticut equivalent.
Contrast With New York Tax
The contrast with New York makes the point. If you live in Greenwich and work in Manhattan, New York taxes your New York wages as a non-resident, as explained in the New York State non-resident guidance. Connecticut then credits that New York tax, because New York is a qualifying jurisdiction. Hence New York tax on your salary is relieved, while British tax on your London flat is not. That asymmetry sits at the heart of every expat tax Connecticut plan we prepare.
Connecticut Residency: When the State Can Tax You
Before the credit question arises, Connecticut must first treat you as a resident. The rules turn on domicile and on a permanent place of abode.
Domicile or a Permanent Home Plus 183 Days
According to Connecticut's resident income tax guidance, you are a resident if Connecticut was your domicile for the whole year. Alternatively, you are a resident if you maintained a permanent place of abode in Connecticut for the whole year and spent more than 183 days there. A rented house counts as a permanent place of abode, whether or not you own it. Consequently, a British family renting in Greenwich on a long lease meets the test in their first full year.
The Arrival Year Is a Part-Year Return
In the year you move, you file as a part-year resident. Connecticut then taxes worldwide income only for the period after you became resident. Income and gains realised before arrival fall outside the state, although Connecticut-source income still counts. Therefore the date you move, and the date you realise large UK gains, shape the expat tax Connecticut result for that year more than any other decision.
The Two Routes Out for a Domiciliary
Leaving is harder than arriving. A Connecticut domiciliary becomes a non-resident only by meeting one of two tests. The first requires no permanent place of abode in Connecticut, a permanent home elsewhere, and no more than 30 days in the state. The second requires presence in a foreign country for at least 450 days in any 548-day period, with no more than 90 days in Connecticut during that span. Accordingly, a family returning to London should keep a day count from the moment they leave, since the expat tax Connecticut claim continues until one test is met.
Federal Residency Runs on Different Rules
Federal residency follows its own tests. A green card makes you a US tax resident from the day it takes effect, while visa holders are tested under the IRS substantial presence test. The federal start date and the Connecticut start date can differ. Additionally, the UK side has its own rules under the statutory residence test guidance in RDR3, including split-year treatment. Aligning all three dates is a core part of our expat tax Connecticut work, and our guide to the first-year choice election covers one of the federal levers.
How Each Type of UK Income Fares in Connecticut
With no foreign credit available, the question becomes which UK income HMRC taxes and which it leaves alone. The answer differs sharply by income type.
UK Rental Income: Taxed Three Times
Britain taxes UK rent in the hands of a non-resident landlord, usually through the Non-Resident Landlord Scheme, with 20% withheld unless you register to receive rent gross. The federal return then taxes the same profit, credited by the UK tax. Connecticut adds 6.99% on top, with no relief. Consequently, UK rent carries the heaviest expat tax Connecticut burden of any income type. For expat tax Connecticut purposes, the UK withholding changes nothing, because Connecticut ignores it. Our guide to stopping the 20% NRL withholding explains the cash-flow side.
UK Property Gains: The Largest Single Exposure
Non-residents pay UK capital gains tax on UK land, now at 18% and 24%, as the HMRC guidance for non-residents sets out. The federal return taxes the gain again, credited by the UK tax, but the 3.8% net investment income tax generally takes no foreign credit. Connecticut then charges 6.99% of the whole gain. For a large London sale, this is the biggest single expat tax Connecticut decision you will face, as the case study below shows. See also our guide to UK non-resident capital gains tax for US persons.
UK Pensions: No UK Tax, Full Connecticut Tax
Under Article 17 of the treaty, a private UK pension paid to a US resident is generally taxable only in the United States. So there is no double tax. Nevertheless, Connecticut taxes the whole payment. Its pension subtraction phases out completely once federal AGI reaches $150,000 for joint filers or $100,000 for single filers, which rules out almost every client we serve. Similarly, the UK State Pension is fully taxable federally, as IRS Publication 915 explains, and Connecticut follows. Our guide to the UK State Pension for Britons in America covers the federal detail.
ISAs, UK Funds and Dividends
An ISA gives no protection in the United States, so its income and gains reach federal AGI and therefore Connecticut. Moreover, UK funds held inside or outside an ISA are usually PFICs, reported on IRS Form 8621, and their punitive federal income flows straight into the Connecticut base. UK dividends suffer no UK withholding for non-residents, so there is no foreign tax at all. Consequently, Connecticut's 6.99% lands on top of the federal charge, making the expat tax Connecticut cost of holding a UK portfolio higher than most families expect.
Timing the Move: Arrival and Departure Planning
Because Connecticut offers no credit, the most powerful tool is timing. Specifically, you control when you become resident and when you realise large British gains.
Sell Before You Arrive
A British national who sells a UK property while still UK resident, and before becoming a US tax resident, pays UK tax only. Neither the IRS nor Connecticut has any claim on that gain. By contrast, the same sale a year later draws federal tax, the net investment income tax and Connecticut's 6.99%. Therefore we always model pre-arrival disposals for clients planning a move, and this is the single most valuable expat tax Connecticut decision available. US citizens are different, because the federal claim exists wherever they live.
Watch the UK Temporary Non-Residence Rule
Selling immediately after leaving Britain is a trap. If you return to the UK within five full tax years, HMRC can tax gains realised while you were abroad under the temporary non-residence rules. Consequently, a sale timed for the gap between UK departure and US arrival needs care on both sides. Our guide to temporary non-residence for Americans explains how the rule interacts with US tax.
Draw Pensions After You Leave Connecticut
Federal law protects retirement income once you move away. Under 4 U.S.C. section 114, a state cannot tax retirement income paid to a non-resident. Accordingly, a family planning to return to London can defer large pension drawings until after Connecticut residency has ended, provided the departure genuinely meets the domicile tests above. That step alone can save 6.99% of every drawing, which makes it a central expat tax Connecticut exit tool.
Keep UK Workdays Treaty-Protected
Many Greenwich professionals still spend weeks in London each year. Under the treaty's employment article, a US resident working in Britain for fewer than 183 days, paid by a non-UK employer and not charged to a UK branch, is generally exempt from UK tax. If those conditions fail, however, HMRC taxes the workdays and Connecticut gives no credit for that UK tax. Therefore keep travel logs and employer arrangements tidy, because a failed treaty claim becomes an expat tax Connecticut cost as well as a UK one, and let our tax treaty optimisation team check the position before the year closes.
Federal Interactions: SALT Cap and Pass-Through Entity Tax
Connecticut tax also interacts with your federal return. For high earners, two federal rules decide how much of the state bill you can deduct.
The 2026 SALT Deduction Cap
The federal deduction for state and local taxes under 26 U.S.C. section 164 is capped at $40,400 for 2026. However, the cap phases down once modified AGI exceeds $505,000, falling to a floor of $10,000. So a household earning $1.4 million deducts only $10,000 of perhaps $100,000 of Connecticut income tax and several thousand dollars of property tax. Consequently, the federal deduction offers little relief for the expat tax Connecticut bill at this income level.
The Elective Pass-Through Entity Tax
Connecticut's pass-through entity tax became elective from the 2024 tax year. An electing partnership or S corporation pays tax at 6.99% on its income, and each individual member claims a Connecticut credit equal to 87.5% of their share. The entity-level tax is deductible federally, outside the SALT cap. Accordingly, for a founder or fund principal with Connecticut business income, the election is usually worth modelling each year as part of the wider expat tax Connecticut review.
Why the Entity Tax Does Not Fix UK Income
The entity tax only helps with business income that runs through a US pass-through entity. It does nothing for UK rent held personally, a UK pension or gains on a London flat. Moreover, a UK limited company is generally a corporation for US purposes, not a pass-through. Therefore the entity tax is a useful tool for your American business income, but it is no substitute for the timing strategies above.
Case Study: The Ashworths Sell a London Flat From Greenwich
The following illustrative case study uses real 2025 and 2026 rules. Names and details are fictional, and we use an exchange rate of $1.32 to the pound for simplicity.
The Facts
Oliver and Clare Ashworth moved from Notting Hill to Greenwich in August 2025 on green cards, so both are US tax residents. Oliver earns $1,250,000 at a Stamford hedge fund. They let their Kensington flat for a net profit of £60,000 ($79,200), and their ISAs produce £18,000 ($23,760) of income. In 2026 they sell a Clapham buy-to-let bought in 2016, making a gain of £500,000 ($660,000). Their Connecticut AGI for 2026 is therefore about $2,012,960.
The UK and Federal Position
As British nationals, they keep the UK personal allowance, so HMRC charges about £11,432 ($15,090) on the rent. On the Clapham sale, HMRC charges 24% after the £3,000 annual exempt amount, which is £119,280 ($157,450). Federally, the rent costs $29,304 at 37% before the credit, which absorbs $15,090. The gain costs $132,000 at 20%, fully covered by the larger UK tax, leaving about $25,450 of excess credit. That excess shelters the federal tax on the ISA income, because both sit in the passive basket. Connecticut, however, has no basket and no credit, which is where the expat tax Connecticut damage begins. However, the net investment income tax adds about $28,090 across the rent and the gain, with no credit.
The Connecticut Bill
Connecticut taxes everything at an effective 6.99%. The British items alone come to $762,960, so Connecticut charges about $53,331 on income on which the Ashworths have already paid HMRC. Specifically, $46,134 of that relates to the Clapham gain. In total, the Clapham sale costs them UK tax of $157,450, federal net investment income tax of $25,080 and Connecticut tax of $46,134. That is $228,664, or 34.6% of the gain.
What Timing Would Have Saved
Had the Ashworths exchanged contracts on Clapham while still UK resident, and before their green cards took effect, they would have paid UK tax of $157,450 and nothing else. Consequently, the late sale cost them about $71,214. This is the core expat tax Connecticut lesson: the credit gap cannot be fixed after the event, only planned around beforehand. In our experience, we see some version of this sequence in most British relocations to Fairfield County.
Compliance Obligations That Come With Connecticut Residency
Becoming a Connecticut resident usually means becoming a US tax resident, and that brings reporting duties that many British arrivals miss.
FBAR and Form 8938 for Your UK Accounts
As US tax residents, you must report UK bank, ISA, pension and investment accounts on the FBAR once their combined value exceeds $10,000 at any point in the year, filed through FinCEN's BSA E-Filing system. Additionally, Form 8938 applies above higher thresholds. A missed FBAR carries serious penalties, and our FBAR and FATCA reporting service handles both filings alongside your returns.
Missed Connecticut Returns
Some families file federally but overlook Connecticut in the arrival year, particularly when a relocation agent handled payroll. Connecticut receives federal return data, so the gap tends to surface. Moreover, when no return is filed, the assessment period never begins to run. If you are behind on federal filings too, our IRS Streamlined filing service can bring the federal side up to date, and we prepare the matching expat tax Connecticut returns in the same engagement.
Estimated Tax Payments
Connecticut expects quarterly estimated payments when withholding does not cover your liability. UK rent and a large London gain have no Connecticut withholding at all. Therefore a sale in the spring should trigger an expat tax Connecticut estimated payment for that quarter, rather than a surprise bill and interest the following April.
How TaxYork Can Help
Our team prepares the complete set of returns a British family in Connecticut needs, and we build each expat tax Connecticut engagement around the three tax systems together.
Joined-Up Returns
We prepare your federal return with Form 1116 and the treaty positions, your Connecticut CT-1040 or part-year return, and your UK Self Assessment where HMRC still taxes you. Consequently, the same figures, exchange rates and dates run through all three, and nothing is taxed twice by mistake. Our expat tax Connecticut reviews also flag UK income that could be restructured before the next tax year.
Planning Before the Event
We model UK disposals, pension drawings and residency dates before you act, because timing is the only reliable fix for the Connecticut credit gap. Furthermore, we check whether an elective entity tax or a restructuring of your American business income is worthwhile each year. For wider cross-border matters, see our cross-border planning service.
Conclusion
The expat tax Connecticut position rewards British families who plan and punishes those who assume the treaty covers everything. Connecticut taxes high earners at an effective flat 6.99%, gives no credit for UK tax, and treats a London property gain exactly like salary. Meanwhile, the federal foreign tax credit still works, but it never reaches the state return. Therefore the families who fare best sell major UK assets before arrival, draw pensions after departure, protect their UK workdays under the treaty, and keep their FBAR and Form 8938 filings current. In summary, the rate is moderate, but the missing credit makes planning essential.
Contact Us
If you live in Greenwich or elsewhere in Connecticut and hold British income, property or pensions, we can prepare your federal, Connecticut and UK returns together and model the timing before you act. Book a consultation with our team, email hello@taxyork.com or call 020 3488 8606. We work with clients in Fairfield County and across the United States, and you can compare costs first with our US-UK tax calculators.
Disclaimer
This article provides general information about US federal, Connecticut and UK tax rules as they stood in September 2026. It is not tax or legal advice for your specific circumstances, and the case study is illustrative only. Tax rules, rates and thresholds change, and the outcome for your family depends on your full facts. Please take professional advice before acting. TaxYork provides US and UK tax return preparation and compliance services; contact us for help applying these rules to your own situation.