When Your Financial Life Crosses Borders, Your Financial Plan Should Too
What UK–US investors, expats, dual citizens and internationally mobile families should know about cross-border wealth planning
For many people, financial planning is already complicated enough. Add a second country, a second currency, different tax systems, pensions in both countries, property overseas and family members living on opposite sides of the Atlantic—and the picture can become significantly more complex.
A recent article from Chase Buchanan highlights an issue that is increasingly relevant for internationally mobile investors: investment performance is only one part of the financial planning equation. Where you live, where your assets are held, where your income originates and where you ultimately expect to spend or pass on your wealth can all influence the outcome of a financial strategy.
For clients of Fyvie Financial, this is particularly important. A financial plan designed around only your UK or US circumstances may overlook what happens when those two financial systems interact.
What Is Cross-Border Financial Planning?
Cross-border financial planning is the process of looking at someone's entire financial life across more than one country.
For a UK–US client, that might include:
UK and US investment accounts
Workplace pensions and US retirement plans
UK or US property
Bank accounts in both countries
Income earned in different currencies
Employer stock or equity compensation
Life insurance
Business interests
Estate-planning documents
Inheritance considerations
Tax residency
Currency exposure
Future retirement plans
The key is not simply to manage each piece independently.
Instead, the goal is to understand how the pieces interact.
That distinction matters because an account or investment that makes sense when viewed from one country's perspective may have different consequences when viewed from the other.
Why This Matters More Than Investment Performance Alone
It is natural to focus on investment returns.
If your portfolio earned 8%, 10%, or 12%, that sounds like a straightforward measure of success.
But for someone living between the UK and US, the actual outcome can be more complicated.
Imagine someone who:
Works in the UK
Is a US citizen
Has a UK workplace pension
Owns a US retirement account
Has investments in both countries
Owns a property in the UK
Expects to retire in the United States
Their financial plan isn't governed by a single set of rules.
Tax residency, reporting requirements, pension rules, currency movements and estate considerations can all become relevant.
As Chase Buchanan's recent commentary points out, relocating can change how capital gains, pensions, investment income and other assets are treated. Decisions made before a move can also have consequences after someone becomes resident somewhere else.
That is why cross-border planning should be viewed as an ongoing process—not something you address once when you move.
Who Should Be Thinking About Cross-Border Planning?
You don't have to be an ultra-high-net-worth investor to have a cross-border financial planning issue.
Americans living in the UK
If you're a US citizen or US tax resident living in the UK, you may still have US tax and reporting obligations.
The IRS generally requires US citizens and resident aliens living abroad to report worldwide income, subject to applicable rules and reliefs. Certain taxpayers may also have additional foreign-asset reporting obligations.
This means your UK financial life doesn't necessarily sit outside your US financial responsibilities.
Britons living in the United States
Moving to the US doesn't necessarily mean you should simply close your UK accounts and start again.
You may have:
UK pensions
UK investments
UK property
UK bank accounts
Inheritance interests
Family financial responsibilities in Britain
The question becomes how those assets fit into your new US-based financial plan.
Dual citizens
Dual citizens can face particularly complex planning considerations because citizenship, residence and asset location can all play different roles.
For example, a US citizen living in Britain may have UK financial products while remaining subject to US worldwide income taxation and certain foreign-account reporting rules.
The IRS notes that FBAR reporting can apply when the aggregate value of certain foreign financial accounts exceeds $10,000 at any point during the calendar year, while Form 8938 can create separate reporting obligations based on different thresholds and circumstances.
Important: these reporting requirements are not the same thing as owing additional tax. They are information-reporting obligations, and the applicable rules depend on the individual's circumstances.
People planning to move
This is one of the most important groups.
If you're planning to move from the UK to the US—or from the US to the UK—the period before the move can be an important planning window.
A transaction that makes sense today may have different consequences after your tax residence changes.
The recent Chase Buchanan article specifically highlights the importance of considering the timing of investment sales, withdrawals and portfolio restructuring around a change in residency.
Families with assets in both countries
Cross-border planning also becomes important when your family spans countries.
For example:
You live in California, your spouse is British, you own a home in the US, have a UK pension, and your children may eventually inherit assets located in both countries.
Your financial plan needs to consider not only how you accumulate wealth, but also how that wealth could move between generations.
Pensions Deserve Particular Attention
Retirement planning can become particularly complicated when your working life spans two countries.
You might have:
A UK workplace pension
A SIPP
A US 401(k)
A traditional IRA
A Roth IRA
Social Security
UK State Pension entitlement
It can be tempting to look at each account separately.
But the more important question is:
How do all of these sources of retirement income work together?
The UK–US tax treaty contains specific provisions addressing pensions and pension schemes, including circumstances involving contributions and benefits from schemes established in the other country.
That doesn't mean every UK pension or US retirement account receives identical treatment in both countries. The details matter.
For someone approaching retirement, questions might include:
Where will I be resident when I retire?
Which currency will I need for my spending?
Which pensions will I draw from first?
How will withdrawals be taxed?
What happens if I move again?
What happens to these assets when I die?
Who will inherit them?
Do my beneficiaries live in the UK or US?
These are planning questions—not simply investment questions.
Estate Planning Is Becoming Even More Important
This is an area that deserves particular attention because UK Inheritance Tax rules changed significantly from 6 April 2025.
The UK replaced its previous domicile and deemed-domicile framework with rules based on long-term UK residence. Under the new rules, long-term UK residents can potentially have overseas assets within the scope of UK Inheritance Tax.
Generally, an individual can become a long-term UK resident after being UK tax resident for either the previous 10 consecutive years or a total of at least 10 years within the previous 20 tax years, subject to the detailed rules. There can also be a period of continuing exposure after leaving the UK.
For someone with assets in both countries, this makes estate planning something worth revisiting—not something to leave until retirement or later in life.
And there is another important change on the horizon.
For deaths occurring on or after 6 April 2027, most unused pension funds and pension death benefits are scheduled to be brought into the value of an individual's estate for UK Inheritance Tax purposes, subject to applicable exemptions and reliefs.
That is particularly relevant for people who have historically viewed their pension primarily as a retirement-income vehicle but also as part of their estate strategy.
Don't Forget Currency Risk
Cross-border planning isn't only about taxes.
It is also about what your money can buy.
Suppose you earn your income in US dollars but expect to spend part of your retirement in the UK.
Or perhaps you receive a UK pension in pounds but live in the United States and pay your bills in dollars.
Changes in the GBP/USD exchange rate can affect the purchasing power of that income.
This doesn't necessarily mean you should try to predict currency markets.
Instead, it means your financial plan should recognize that the currency of your assets and the currency of your future spending may not be the same.
A good planning conversation might therefore consider:
Which currency your future expenses will be in
Which currency your income will be received in
Where your investments are held
When you expect to move money between countries
How much currency fluctuation your plan can reasonably absorb
What Can You Do Now?
If you have financial ties to both the UK and US, you don't necessarily need to make a major change to your portfolio.
The first step is often simply to take inventory.
1. Map your financial life
Create a list of everything you own and owe in each country.
United Kingdom
Bank accounts
Investments
Pensions
Property
Business interests
Insurance
United States
Bank accounts
Brokerage accounts
401(k)s
IRAs
Property
Business interests
Insurance
Then identify where your income comes from and where you expect to spend it.
2. Confirm your current and anticipated tax residency
Your tax residence can have significant implications for how your assets and income are treated.
Don't assume that moving physically from one country to another automatically answers every tax question.
The UK–US tax treaty includes residency provisions and tie-breaker rules for certain situations in which an individual may otherwise be considered resident in both countries.
This is an area where qualified tax advice is particularly important.
3. Review your pensions before making changes
Before transferring, consolidating or withdrawing from a pension, understand the potential implications in both countries.
A decision that appears straightforward from a UK perspective may require additional analysis from a US perspective—and vice versa.
4. Review your investment accounts
Ask:
“Is every account I own still appropriate for my current country of residence and long-term plans?”
This is especially important when you move countries.
Don't automatically assume that an account that was tax-efficient or convenient in one country remains so after your move.
5. Review your estate plan
If you have assets or family in both countries, review:
Wills
Trusts
Beneficiary designations
Powers of attorney
Life insurance
Property ownership
Pension beneficiaries
And make sure the documents work together rather than treating the UK and US as completely separate financial worlds.
6. Review your currency exposure
Think about the currencies in which you:
Earn → Save → Invest → Retire → Spend
If those currencies don't match, make sure your financial plan accounts for that.
7. Coordinate your professional team
Cross-border planning often requires collaboration between professionals.
Depending on your circumstances, that could include:
Financial adviser
↓
Tax professional
↓
Estate-planning attorney/solicitor
↓
Other specialists
The objective isn't necessarily to have one professional do everything.
It is to make sure the advice you're receiving fits together.
The Biggest Takeaway
Cross-border financial planning isn't simply about reducing taxes or finding the highest-performing investment.
It's about understanding the whole financial picture.
Your investments are connected to your tax residency.
Your tax residency is connected to your income.
Your income is connected to your retirement plans.
Your retirement plans are connected to your pensions.
And your pensions, property and investments may ultimately be connected to your estate and the people you want to leave your wealth to.
That's why a financial plan should evolve when your life does.
If you are moving between the UK and US, already have financial interests in both countries, or expect your retirement or family circumstances to span both sides of the Atlantic, now is a good time to ask:
Does my financial plan account for both countries—or am I managing each side separately?
At Fyvie Financial, cross-border planning is about looking at the bigger picture and helping clients coordinate the financial decisions that come with living, working, investing and planning for the future between the UK and United States.
Important: This article is for general educational purposes and is not individualized tax, legal or investment advice. UK and US tax and estate rules are complex and can change. The appropriate treatment depends on an individual's citizenship, residence, assets, transactions and other circumstances. Clients should consult qualified tax and legal professionals regarding their specific situation.
