US-UK Tax Specialists for High Earners in Boston
Boston's biotech, finance, and healthcare executives with UK income, pensions,s or property face two overlapping tax systems at once, and the US-UK tax specialists Boston families rely on exist to untangle them. The Massachusetts surtax, the 183-day residency test, and IRS rules like FBAR all need to be coordinated, so nothing slips through the cracks.
by the TaxYork Cross-Border Tax Team—evaluated by a dual-qualified adviser (CPA/Enrolled Agent) from the US and the UK.
Why Boston high earners need US-UK tax specialists in Boston
A Boston-based biotech executive or finance director with a UK pension, a London flat, or a British spouse is not filing a simple return. Massachusetts layers its own flat income tax and a 4% surtax on top of federal rules, while UK income, gains, and accounts trigger a separate set of IRS disclosure obligations. Generic national expat guides skip the Massachusetts specifics, and generic Boston CPAs rarely know FBAR, Form 8938, or the treaty-saving clause in any depth — which is exactly the gap US-UK tax specialists' Boston clients need bridged.
Wages, interest, and most capital gains are all subject to a flat 5% tax in Massachusetts, although short-term capital gains are subject to a higher 8.5% tax. On top of that sits the so-called "Millionaires Tax": a 4% surtax on taxable income above a set threshold, pushing the combined top state rate to 9% for the highest earners.
Massachusetts state tax on top of federal and UK obligations
Layer
Rate / Threshold
Applies to
Massachusetts standard rate
5% flat
Wages, interest, and most capital gains
Massachusetts short-term gains
8.5%
Assets held one year or less
4% surtax (TY2025)
Taxable income over $1,083,150
Combined top rate of 9%
4% surtax (TY2026, inflation-adjusted)
Taxable income over $1,107,750
Combined top rate of 9%
Federal NIIT
3.8% on investment income
MAGI over $200,000 single / $250,000 MFJ
The 4% surtax catches Boston executives with a UK property sale, a large pension crystallization, or a one-off equity payout in the same year — none of which is offset by UK tax paid, because the surtax is a state-level charge with no foreign tax credit mechanism. This is where US-UK tax specialists, Boston advisers, earn their fee: sequencing a UK disposal or pension drawdown to avoid pushing a client over the threshold in a single tax year.
Who does this actually affect around Boston?
Cambridge and the Longwood Medical Area house a dense concentration of biotech scientists, clinical directors and executives, many recruited from — or seconded to — UK research groups and pharmaceutical companies. Salary bands in Boston biotech commonly stretch well into six figures at senior levels, and it takes only one liquidity event — a UK share option exercise, a lab licensing bonus, or a UK property sale timed badly — to tip a household over the surtax threshold in a single year.
The same pattern appears in Boston's finance and healthcare executive ranks, where bonus structures and UK-linked deferred compensation create similar single-year income spikes. None of this is exotic; it is simply what happens when a high income meets two tax systems that were never designed with each other in mind, and it is precisely why cross-border planning has to happen before the transaction, not after the return is filed.
When does the 183-day rule make you a Massachusetts tax resident?
Massachusetts treats you as a statutory resident if you are domiciled in the state or keep a permanent place of abode there and spend more than 183 days in Massachusetts. Any portion of a day counts during the tax year. This applies to executives who keep a Boston home while working extended stints in the UK, and it operates entirely independently of US federal residency and UK statutory residence rules.
Why the state test matters even after you qualify as a UK resident
Under UK rules, you might clearly be a UK tax resident for the year. Under the US-UK treaty, you might be treated as a US nonresident for federal purposes in some scenarios — but Massachusetts runs its own statutory residency test and does not automatically follow either. A Boston condo kept "just in case," combined with more than half the year spent in Massachusetts on trips home, can trigger full state residency and Massachusetts tax on worldwide income, regardless of UK tax already paid.
The trap is easy to walk into without noticing. A finance director relocated to London for an 18-month assignment might sublet her Boston apartment for part of the year but keep it furnished and available between tenancies, then return for board meetings, family visits and holidays that add up to well over half the calendar year. Massachusetts counts every one of those days, including partial days, and it does not care that UK PAYE was withheld correctly or that a UK self-assessment return was filed on time. The safest approach is to deliberate from the date of departure deliberately, keep documentary evidence — flight records, lease dates, utility bills — and review the position with an adviser before, not after, the 183-day mark is reached.
FEIE or Foreign Tax Credit — which works better for Boston professionals with UK income?
For most Boston high earners with UK salary or self-employment income, the Foreign Tax Credit usually beats the Foreign Earned Income Exclusion because UK tax rates on income above roughly £50,000 generally exceed US rates, leaving unused credit to carry forward. The FEIE only shelters earned income up to a capped amount and does nothing for investment income, rental income, or the Massachusetts surtax.
FEIE vs Foreign Tax Credit at a glance
Foreign Earned Income Exclusion
Foreign Tax Credit
2025 cap
$130,000 per qualifying person
No cap — credit follows tax actually paid
2026 cap (inflation-adjusted)
$132,900 per qualifying person
No cap
Does it cover investment income?
No
Yes, with limitations
Best suited to
Lower UK earners, single-income households
Higher earners in higher UK tax bands
The Foreign Earned Income Exclusion figures rose again for 2026, reflecting the recent inflation adjustments. However, the choice between FEIE and Foreign Tax Credit still needs to be modeled year by year, particularly because the Foreign Tax Credit — unlike the exclusion — cannot offset the 3.8% Net Investment Income Tax on dividends, interest, and capital gains.
Behind on US filings while living between Boston and the UK?
Falling behind on US returns while connected to the UK is common and can be resolved through the IRS Streamlined Filing Compliance Procedures, provided the failure was non-wilful. The process generally requires three years of amended returns, six years of FBAR filings, and a signed certification explaining the oversight — most Boston clients we see qualify for the Streamlined Domestic Offshore Procedures with a modest 5% penalty rather than the far larger civil penalties for wilful non-disclosure.
Boston's biotech and finance sectors draw in professionals who spent years working on UK secondment or holding a UK pension before returning stateside, often unaware that a UK pension or ISA must be reported on an FBAR. US-UK tax specialists at Boston firms handle this routinely through streamlined filing compliance procedures, and the same clients often need the mechanics of FBAR and Form 8938 explained side by side — covered in our related piece on the role of FBAR and Form 8938 in a streamlined submission.
Case study: a Boston biotech director's UK pension catch-up
A biotech director in Cambridge, Massachusetts, had a UK workplace pension worth roughly £180,000 from a prior London posting that was never reported on FBAR or Form 8938. She had assumed a foreign pension only mattered for UK tax purposes and had no idea the account needed to be disclosed to the IRS at all, which is a common and entirely understandable misunderstanding among returning secondees. Working with US-UK tax specialists Boston Advisers, she filed under the Streamlined Domestic Offshore Procedures: three amended returns, six years of FBARs, and a 5% penalty on the highest year-end pension value — resolving the exposure for a fraction of what wilful penalties would have cost, and closing the matter permanently rather than leaving it as an open risk hanging over future US filings.
UK property, treaty relief, and the Boston connection
Boston high earners who still own a UK home face US capital gains tax on the sale of any portion above the Section 121 exclusion, even where UK Private Residence Relief wipes out the UK bill entirely — a mismatch that catches people out every year. Our related article on US and UK tax consequences of selling a UK home walks through the exclusion, the FX mortgage-repayment trap under Section 988, and how the Foreign Tax Credit interacts with UK Capital Gains Tax.
The treaty's saving clause means the US still taxes its citizens on worldwide income, no matter where they live. Hence, a Boston-based dual national selling a London property or crystallizing a UK pension needs both sides of the calculation done together, not filed separately by two advisers who never speak. The British Consulate General serving Massachusetts is based in Cambridge and covers British nationals across the wider New England region, reflecting just how many UK-connected households live in and around Boston.
Founders, divorce, and other cross-border complications
Boston's startup and biotech scene means some high earners also run a UK limited company on the side, which brings Form 5471 reporting and possible GILTI exposure, plus a Totalization Agreement question over UK versus US social security contributions — details covered in our piece on what happens when you're behind on US taxes after starting a UK business, drawing on the US-UK Totalization Agreement rules. Divorce across the same border raises its own traps, particularly when Section 1041's tax-free transfer rule fails for a spouse who is a nonresident alien — explored fully in minimizing US and UK tax when divorcing across borders.
Capital gains work the same way for any Boston household with UK-sourced investment income: gains are taxed on worldwide income for US citizens regardless of residence, and the interaction with the 3.8% NIIT and UK Capital Gains Tax rates needs coordinated planning, not two separate filings — a theme we cover in depth in capital gains for US expats explained for wealthy US-UK dual filers.
Talk to TaxYork about your Boston and UK tax position.
If you're a Boston-based high earner juggling Massachusetts state tax, UK income, or a UK pension, our US-UK tax specialists, whom Boston clients rely on, can map out the Massachusetts surtax exposure, the FEIE versus Foreign Tax Credit position, and any overdue FBAR or Form 8938 filings in a single coordinated plan. Email hello@taxyork.com, call 020 3488 8606, or visit taxyork.com to book a consultation built around both tax systems at once.