Moving to the United States is one of the most significant financial events of your life and not just because of the cost of the move. It is because the moment you become a US tax resident, your entire global financial picture changes. The IRS is interested in your UK pension, your ISA, your UK bank accounts, your UK property, your UK investments, and any income you earn anywhere in the world. Most of that interest comes with reporting obligations, and some of it comes with tax.

The good news is that the pre-arrival window is the most valuable planning period you will ever have. Decisions made before you cross the US tax residency threshold can save tens of thousands of pounds. Decisions ignored until after you arrive can create obligations that are expensive, difficult to unwind, and in some cases impossible to avoid.

This checklist is designed for British citizens moving to the United States. It covers what to do before you leave the UK, what to address in your first weeks in America, what your first US tax return requires, and what ongoing obligations you carry every year thereafter. It is not a substitute for specific professional advice, but it tells you exactly what questions you need to be asking and when.

What this article will cover

Before you arrive:

• The substantial presence test and exactly when you become a US tax resident

• The pre-arrival window and why it is the most valuable planning period you will ever have

• Whether to take your pension commencement lump sum before you go

• ISA and UK investment decisions to make while still a UK resident

• UK property timing and the capital gains position before departure

• Voluntary National Insurance contributions and protecting your State Pension

• Deregistering correctly from HMRC and what happens to your UK self-assessment obligation

• What to do with UK bank accounts, ISAs, and investment accounts before crossing the threshold

The first 90 days in the US:

• Getting your Social Security Number and ITIN if needed

• Opening a US bank account as a new arrival

• Understanding your state of residence and its tax implications

• Whether your visa type affects your tax status

• What the IRS considers your tax home

Your first US tax return:

• The dual status return and what it means for the year you arrive

• What worldwide income reporting actually covers

• The treaty election for your SIPP and how to make it on Form 8833

• FBAR and Form 8938 thresholds and deadlines

• Whether your UK employer pension requires Form 3520 and 3520-A

• Reporting UK rental income on a US return

• Foreign tax credits and how they interact with UK tax already paid

Ongoing annual obligations:

• The compliance calendar every UK expat needs

• What triggers a UK tax return even after you leave

• State pension uprating and what you are entitled to as a US resident

• Voluntary NI contributions while abroad

Common and expensive mistakes:

• Assuming the ISA is tax-free in the US

• Missing the FBAR deadline

• Not making the pension treaty election

• Taking the pension lump sum after arriving rather than before

• Choosing the wrong state to settle in

Part 1: Before You Leave the UK

The period before you establish US tax residency is when you have the most freedom to act. Once you are a US tax resident, the IRS has a claim on your worldwide income and certain transactions that would have been straightforward in the UK become significantly more complex. The decisions in this section should ideally be made and implemented before you arrive.

Understanding When You Become a US Tax Resident

The first thing you need to know precisely is when you will become a US tax resident. This is not the same as when you arrive. It is not the same as when your visa starts. It is determined by one of two tests.

If you hold a green card, you are a US tax resident and US tax residency begins when lawful permanent residence is established, which is generally when you enter the United States as a permanent resident or adjust status.

If you are entering on a work visa, student visa, or any non-immigrant visa that does not grant lawful permanent residence, you become a US tax resident when you meet the Substantial Presence Test. This test counts the days you are physically present in the United States across a rolling three-year window. You are treated as a US tax resident for a calendar year if you are present in the US for at least 31 days during that year and the sum of days present in the current year, one third of days in the prior year, and one sixth of days in the year before that totals 183 days or more.

The year you first meet the Substantial Presence Test is normally your first year of US tax residency. In that year you normally file a dual status return, covering the period before your residency start date under non-resident rules and the period from your residency start date under resident rules.

• Know your residency start date before you make any financial decisions. Everything in this checklist depends on whether a transaction happens before or after that date. If you are unsure, calculate it before you act.

The Pre-Arrival Planning Window

The period between deciding to move and actually becoming a US tax resident is when the most effective planning happens. The following decisions should be addressed during this window.

Your Pension Commencement Lump Sum

If you have a defined contribution pension such as a SIPP or a workplace pension, and you are over 55 (rising to 57 from 2028), you are entitled to take up to 25% of the fund as a tax-free lump sum under UK law. In the UK it is completely free of income tax. In the United States it could be taxable as ordinary income if you take it as a US tax resident. See UK Pensions and U.S. Tax: The 25% Pension Lump Sum and US Tax

Taking the pension commencement lump sum before you become a US tax resident is one of the most significant tax planning opportunities available to a British person moving to America. Once taken while a UK resident, the lump sum is outside the pension wrapper, has been received free of UK tax, and is not subject to US tax because you were not yet a US tax resident when you received it (unless of course, you are a US citizen!)

The invested proceeds will then be subject to US tax rules going forward, but that is a manageable position. Not taking the lump sum before departure and then crystallising it as a US resident at a 22% or 24% federal rate, plus state income tax in most states, on what could be a six-figure sum is a very expensive oversight.

See our dedicated article: The 25% Pension Lump Sum and US Tax, for the full treaty analysis and IRS guidance on this point.

Your ISA

An ISA is one of the most common financial assets a British person holds and it is one of the most misunderstood from a US tax perspective. In the UK an ISA is completely tax-free. Income, dividends, interest, and capital gains within an ISA are exempt from UK tax. That treatment does not transfer to the United States.

For a US tax resident, an ISA is a foreign financial account. The income and gains arising within it are taxable in the US as ordinary income or capital gains in the year they arise. There is no treaty provision that protects the ISA's tax-free status in the same way the pension treaty election can defer SIPP growth.

Before you move, consider whether to encash the ISA while you are still a UK resident. If you do, you crystallise any gains as a UK resident, which may be within your UK capital gains annual exemption or at UK CGT rates, and you arrive in the US with cash rather than a foreign financial account generating taxable income annually. If you keep the ISA, you must report the income and gains each year on your US return and potentially include the account on your FBAR and Form 8938.

The ISA also cannot be added to once you are no longer a UK resident, although UK rules allow contributions if the person remains UK resident for tax purposes or is a Crown employee overseas, so its usefulness as a savings vehicle effectively ends when you leave. Keeping an ISA after moving for some people may not be the optimal financial decision.

See our dedicated article: ISAs and UK Investments Under US Tax: What Stops Being Tax-Free, for the full analysis.

UK Property

If you own UK property and are considering selling it, the timing of that sale relative to your US tax residency start date has significant implications. As a UK resident selling UK residential property, you pay UK capital gains tax at 18% or 24% depending on your total income, with your annual CGT exemption available. As a US tax resident selling the same property, you pay US capital gains tax and you file a UK non-resident return also paying UK CGT, with a foreign tax credit available to prevent full double taxation. However, the US and UK CGT calculation methods differ, and the interaction is not always clean.

If you have a property with a significant gain and you are planning to sell it anyway, doing so before becoming a US tax resident may remove the US complication entirely. If you intend to keep the property and rent it, rental income is taxable in both the UK and the US from the moment you are a US tax resident, with credit available for UK tax paid.

See our dedicated articles: Selling UK Property After Moving to the US and US Tax for Foreign Owners of Rental Property, for the full analysis.

Voluntary National Insurance Contributions

Your UK State Pension entitlement is built on National Insurance contribution years. You need 35 qualifying years for the full new State Pension and at least 10 years for any payment at all. If you have gaps in your NI record, you can make voluntary Class 2 or Class 3 contributions to fill them, and you can continue doing so for a period after leaving the UK.

The cost of voluntary NI contributions is modest relative to the lifetime value of additional State Pension income. Class 3 voluntary contributions for 2024/25 are £824.20 (2025/26 £923.00) per year. Each additional qualifying year adds approximately one thirty-fifth of the full State Pension to your annual entitlement, currently worth around £310 per year for life. The payback period is typically under three years.

Check your NI record on the HMRC website before you leave and assess whether filling gaps makes financial sense. There are time limits on how far back you can go and deadlines for certain years that should not be missed.

Deregistering Correctly from HMRC

Leaving the UK does not automatically end your UK tax obligations. You must notify HMRC that you are leaving and your UK tax residency will be determined under the UK Statutory Residence Test, which is a separate analysis from the US Substantial Presence Test. You can be non-UK resident for tax purposes before you leave the country if you meet the conditions.

You will need to complete a P85 form to notify HMRC if you were employed. If you are self-employed or have a UK self-assessment record, you must continue filing UK returns for any year in which you have UK-source income, including rental income, pension income, and interest, even after you become non-UK resident.

The split year treatment rules may apply in your year of departure, splitting the UK tax year between a UK resident period and a non-UK resident period, which can affect how income in that year is taxed.

UK Bank Accounts and Financial Accounts

You are legally permitted to keep your UK bank accounts after moving to the US. However, once you are a US tax resident, those accounts must be reported annually on the FBAR if the aggregate value of all foreign accounts exceeds ten thousand dollars at any point during the year. They may also need to be included on Form 8938 if the reporting thresholds are met.

Interest earned on UK bank accounts is taxable as ordinary income on your US return. Some UK banks may restrict services to non-UK residents or require you to notify them of your change of address. Check your bank's terms before you move and ensure they have your US address once you arrive. See also FBAR and FATCA for UK Expats: Reporting Your UK Accounts to the IRS

Part 2: Arriving in the United States

The first weeks and months in the US involve a series of practical steps that are also financially significant. Getting the administrative foundations right early makes everything that follows more straightforward.

Your Social Security Number

A Social Security Number is your primary tax identification number in the United States. If you are arriving on a work visa that permits employment, you can apply for a Social Security Number through the Social Security Administration once you arrive and have your visa stamp in your passport. You will need your visa documentation, passport, and proof of address.

Without a Social Security Number you cannot file a US tax return, open most bank accounts, or be paid by a US employer through payroll. Getting this sorted in the first few weeks is a priority.

Individual Taxpayer Identification Number

If you are not eligible for a Social Security Number, for example if you are arriving on a visa that does not permit employment but you still have US tax filing obligations, you will need an Individual Taxpayer Identification Number, known as an ITIN. This is obtained by filing Form W-7 with the IRS, supported by certified copies of identity documents. The process takes several weeks and should be started promptly if you need it for a filing deadline.

Opening a US Bank Account

Opening a US bank account as a new arrival can be more difficult than expected. Traditional banks typically require a Social Security Number, a US address, and sometimes a credit history. Some banks are more accommodating to new arrivals than others. Chase, HSBC, and Citibank all have services designed for international customers, and HSBC in particular has a relationship with Barclays in the UK that can help with international transitions.

Fintech alternatives such as Wise, Revolut, and Charles Schwab's international account can provide interim banking functionality while you establish a full bank relationship. Wise in particular is useful for managing GBP and USD in the same account and for receiving UK payments efficiently.

Understanding Your State of Residence

The state where you establish domicile has significant tax implications. The United States has a federal tax system and a separate state tax system. Nine states have no state income tax: Florida, Texas, Nevada, Washington, Wyoming, South Dakota, Alaska, Tennessee, and New Hampshire. If you have flexibility in where you settle, this is worth considering.

Florida is the most popular destination for British expats in the United States and has no state income tax. For someone with a UK pension, UK investment income, and UK rental income, avoiding state income tax on top of federal tax is a meaningful financial advantage.

Your state of residence for tax purposes is where you are domiciled, meaning where you intend to make your permanent home. Simply having an address in a state does not automatically make it your tax domicile if your intent is to move elsewhere. But once you are settled, file a state return where required and ensure your domicile is clearly established in the state you intend.

Visa Status and Tax Treatment

Your visa category affects your tax status in ways that are not always obvious. Most work visas, including H-1B, L-1, and O-1, result in you being treated as a resident alien for tax purposes once you meet the Substantial Presence Test. That means you are taxed on worldwide income like a US citizen.

Certain visa holders are exempt individuals for Substantial Presence Test purposes, meaning their days in the US do not count toward the 183-day threshold. These include F, J, M, and Q visa holders who are students or exchange visitors for limited periods, and J and Q visa holders who are teachers or trainees. If your visa falls into an exempt category you should confirm your tax status with a cross-border tax advisor before assuming you are a US tax resident.

Part 3: Your First US Tax Return

The year you arrive in the United States is likely to be your most complex tax year. You will file a dual status return covering part of the year as a non-resident and part as a resident, and you will need to address a range of UK financial assets that suddenly fall within the US reporting framework. Getting the first return right establishes the foundation for everything that follows.

The Dual Status Return

In your year of arrival, your US tax return covers two periods. Before your US residency start date you are a non-resident alien and only US-source income is taxable in the US. From your residency start date onwards you are a resident alien and worldwide income is taxable. The return is marked as a dual status return and requires separate calculations for each period.

The dual status year is technically more complex than a standard resident return and more complex than a standard non-resident return. Common errors include double-counting income that was earned before residency started, incorrectly applying deductions, and failing to claim the correct treaty benefits for the pre-residency period.

Worldwide Income Reporting

From your residency start date, you report all worldwide income on your US return. This includes your UK salary if you were still employed in the UK for part of the year, UK rental income, UK interest and dividends, UK pension income if you are of pension age, and any other income from any source globally. The foreign tax credit on Form 1116 allows you to offset UK tax paid against your US tax liability on the same income, preventing double taxation in most cases but not always eliminating it entirely.

The Pension Treaty Election

If you have a UK SIPP or other personal pension, you should make the Article 18(5) treaty election in your first US tax return to defer US taxation on income accruing within the pension. This election is made on Form 8833, Treaty-Based Return Position Disclosure, attached to your Form 1040 or via statement under Rev. Proc. 2002-23. You cite the US/UK treaty and Article 18(5), identify the pension, and state that you are electing to defer tax on income that would be exempt from UK tax if you were a UK resident.

See our dedicated articles on UK Pensions and US Tax and the Treaty Election for a full explanation of this election and its implications.

FBAR: FinCEN Form 114

If the aggregate value of all your foreign financial accounts exceeds ten thousand dollars at any point during the calendar year, you must file the FBAR by April 15, with an automatic extension to October 15. This is filed separately from your tax return through the FinCEN BSA E-Filing System. It covers all foreign bank accounts, investment accounts, UK bank accounts, and UK investment accounts. For pension accounts that have a specific monetary value, including your SIPP - There is no explicit FinCEN rule stating SIPPs must be reported, and whether a SIPP is reportable on FBAR is a debated practitioner position
It does not cover your defined benefit pension if you have one, as that does not have a specific account balance.

• The FBAR penalties for non-wilful failure are up to ten thousand dollars per form per year. For wilful failure they can be fifty percent of the account balance per year. These are among the most severe penalties in the US tax system. Missing the FBAR is not a minor oversight.

Form 8938

Form 8938, Statement of Specified Foreign Financial Assets, is filed with your tax return and covers foreign financial assets above certain thresholds. For a single filer living in the US, the threshold is fifty thousand dollars on the last day of the year or seventy-five thousand dollars at any point during the year. For married filing jointly the thresholds are one hundred thousand and one hundred and fifty thousand dollars respectively. The FBAR and Form 8938 are separate filings and one does not satisfy the other.

Form 3520 and Form 3520-A

If you have a SIPP and take the position that it is a foreign trust for US tax purposes, you may need to file Form 3520 and a substitute Form 3520-A. Form 3520-A has an earlier deadline of March 15, distinct from the April 15 deadline for your main return. If you are relying on the treaty position that the SIPP is a pension scheme rather than a foreign trust, you still need to document that position carefully and consistently.

See our dedicated article on UK Pensions and US Tax for a full explanation of the Form 3520 debate and the two professional positions.

UK Rental Income

If you own UK property that you rent out, the rental income is taxable in both the UK and the US from the moment you are a US tax resident. In the UK you file a UK Self Assessment return. In the US you report the gross rental income and deduct allowable expenses including mortgage interest, letting agent fees, repairs, and insurance. The UK tax paid on the net rental income is credited against the US tax liability on that income through Form 1116.

The UK and US rules on allowable deductions differ in some respects, and the exchange rate used for converting sterling income and expenses into dollars can create timing differences. Getting the first year rental income calculation right on both sides is important because it establishes the cost basis and depreciation schedule for the US return going forward.

Choosing Your Filing Status

Your US filing status, whether single, married filing jointly, married filing separately, or head of household, affects your tax brackets, standard deduction, and eligibility for various credits and deductions. If you are married to a non-US person who is also not a US tax resident, you have the option to make an election to treat your spouse as a US resident for tax purposes, which allows you to file jointly. This election has significant implications for both of you and should be carefully considered with professional advice before making it.

Part 4: Annual Obligations Going Forward

Once you are established as a US tax resident, the annual compliance cycle becomes routine but it does not become simple. The following obligations apply every year for as long as you are a US tax resident with UK financial assets or income.

Annual Compliance Calendar

January and February

• Gather UK account statements for the prior year showing year-end balances and income received

• Obtain SIPP valuation statement from your provider

• Collect UK rental income and expense records for the prior year

• Receive UK P60 or pension income statements if applicable

• Check HMRC self-assessment obligations for the prior UK tax year

March 15

• Form 3520-A deadline if you are filing as a substitute trustee for your SIPP

• Extension request available if needed, extending to September 15

April 15

• US federal tax return Form 1040 due, including Form 8833 treaty election, Form 1116 foreign tax credit, Form 8938 if above threshold, and Form 3520 if applicable

• FBAR FinCEN Form 114 due, with automatic extension to October 15

• State tax return due in most states

• Estimated quarterly tax payment Q1 due

June 15

• Estimated quarterly tax payment Q2 due

• Special extended filing deadline for US citizens and residents living abroad if applicable

July 31

• UK self-assessment paper return deadline if you still file in the UK

September 15

• Estimated quarterly tax payment Q3 due

October 15

• Extended US federal return deadline if extension was requested

• Extended FBAR deadline

January 31 following year

• UK self-assessment online return deadline

• UK non-resident landlord return deadline if you receive rental income

UK State Pension Uprating

One piece of genuinely good news for British expats in the United States is that your UK State Pension is uprated annually, unlike the frozen pensions received by British expats in Australia, Canada, New Zealand, and South Africa. The uprating applies because the US and UK have a reciprocal social security agreement. Your State Pension increases in line with the triple lock each year regardless of where you live, provided you live in the United States.

This is widely misunderstood in the British expat community. If you have friends or family who have retired to Australia and receive a frozen pension, the position for US-based expats is different and more favourable.

Voluntary National Insurance after Arrival

Once you are in the US and have stopped paying UK National Insurance through employment, you can continue making voluntary contributions to protect or build your State Pension entitlement. Class 2 contributions are available to those who are self-employed abroad and are significantly cheaper than Class 3. Class 3 contributions are available to anyone not eligible for Class 2. You can pay online through HMRC's website. Check your NI record regularly through the government gateway and fill gaps while the option remains open, as deadlines apply to older years.

Part 5: The Mistakes That Cost the Most

These are the errors that come up repeatedly among British expats in the US. They are listed here not to frighten you but because knowing about them in advance is the only way to avoid them.

Assuming the ISA is Tax-Free in the US

It is not. This is the single most common misconception among British expats. Every pound of interest, dividend, and capital gain inside your ISA is taxable in the US in the year it arises. The UK tax exemption does not travel with you. Many people discover this years after moving when a US tax preparer asks for their foreign account information for the first time.

Missing the FBAR Deadline

The FBAR is filed separately from your tax return, through a different government system, with a different deadline. It is easy to forget, especially in the first year when everything is new. Missing it is not a minor compliance gap. The penalties are severe and the IRS has been actively enforcing FBAR obligations.

Not Making the Pension Treaty Election

The Article 18(5) treaty election to defer US taxation on pension accumulation must be made every year on Form 8833. Many UK expats, and many US tax preparers who are unfamiliar with the UK pension position, simply do not know this election exists. Failing to make it means the IRS could treat annual growth within the SIPP as currently taxable income. Discovering years later that the election was never made creates a difficult and expensive remediation problem.

Taking the Pension Lump Sum After Arriving

As covered in detail above and in our dedicated article, taking the 25% pension commencement lump sum as a US tax resident is almost certainly a taxable event in the US. The planning opportunity is to take it before you become a US tax resident. Many people simply do not know this until it is too late.

Choosing the Wrong State

The difference between living in Florida with no state income tax and living in California with a top state income tax rate of 13.3% is material for someone with UK pension income, UK rental income, and UK investment income on top of their US earnings. The choice of state is a financial decision as much as a lifestyle decision, and it is worth factoring in before you settle.

Not Notifying HMRC Correctly

Simply moving abroad does not end your UK tax obligations. HMRC needs to be notified, your tax residency status needs to be determined under the UK Statutory Residence Test, and you may continue to have UK self-assessment obligations for years after departure if you have UK-source income. Many people stop filing UK returns prematurely and create an exposure that becomes complicated to resolve.

Using a General US Tax Preparer Who Does Not Understand the UK Position

This is perhaps the most expensive mistake of all, not because it leads to obvious errors but because it leads to missed opportunities and incorrect positions that are hard to detect. A general US tax preparer will complete your return correctly for your US income. They may have no idea that the ISA is taxable, that the pension treaty election exists, that the PCLS may require specific analysis, or that the SIPP may require Form 3520-A. The cost of using the wrong advisor is not just the fee. It is the cumulative effect of years of incorrect filings.

Part 6: Finding the Right Advisor

The adviser you need for a UK to US move is not a standard US CPA, and not a standard UK accountant. You need someone who understands both tax systems, the interaction between them, and the specific treaty provisions that govern the most important assets British people carry into the United States.

The practical test is whether your advisor can explain the Article 18(5) pension treaty election, the FBAR reporting requirements for a SIPP, the US treatment of the 25% pension lump sum, and the ISA position without hesitation. If they cannot, they are not the right person for this work, regardless of their general qualifications.

You should also expect your US and UK tax positions to be coordinated rather than handled in isolation. The foreign tax credit only works correctly if both sides of the calculation are done consistently. A UK accountant preparing your non-resident landlord return and a US advisor preparing your Form 1040 who have never spoken to each other is a common and expensive arrangement.

About Antravia Advisory

Antravia Advisory is a cross-border tax and advisory firm founded by a chartered accountant with 25 years of experience in international tax and financial architecture. We specialise in advising British expats in the United States, international founders operating across borders, and complex businesses with cross-border structures. We work with clients who need someone who understands both systems from the inside.

antraviaadvisory.com | contact@antravia.com

Disclaimer: This article is published for informational purposes only and reflects research, professional analysis, and our perspective on a complex and evolving area of cross-border tax law. It does not constitute legal, tax, or accounting advice. Individual circumstances vary and regulations change. Readers should obtain specific professional advice before making financial or tax decisions related to an international move. Antravia Advisory does not accept liability for reliance on the content of this article.

Our UK Expats in US Series

UK Citizens Moving to the U.S.: Tax Issues to Understand Before You Arrive
ISAs and UK Investments Under U.S. Tax: What Stops Being Tax-Free
Selling UK Property After Moving to the U.S.: Capital Gains and Timing Risks
UK Pensions and U.S. Tax: What Happens to Your SIPP When You Move to America
UK Pensions and U.S. Tax: The 25% Pension Lump Sum and US Tax
US–UK Tax Treaty Explained: Dual Residency, Pensions, and Cross-Border Tax Planning for UK Expats
FBAR and FATCA for UK Expats: Reporting Your UK Accounts to the IRS
FIRPTA Explained: U.S. Tax Withholding When Foreign Owners Sell Property
U.S. Tax for Foreign Owners of Rental Property: A Guide for UK Investors

Disclaimer:
Content published by Antravia is provided for informational purposes only and reflects research, industry analysis, and our professional perspective. It does not constitute legal, tax, or accounting advice. Regulations vary by jurisdiction, and individual circumstances differ. Readers should seek advice from a qualified professional before making decisions that could affect their business.

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