Tax Services US/UK for Families: Returns, Accounts, Gifts and Estates

Tax services US/UK for families bring every member's US and UK filings into one plan: the American spouse's Form 1040 and FBAR, the other spouse's Self Assessment, the children's savings, gifts between spouses and an estate plan that works under both systems. The returns are the visible part. The value lies in making sure a choice on one return does not create a problem on another.

This guide is for households where at least one person has US tax obligations and the family lives, saves or owns property in the UK, or the other way round. It sets out who files what, which accounts are reported, how gifts and estates work for a mixed-nationality couple, and what a well-scoped engagement covers. If you are still comparing providers in general, our plain-English guide to tax services US/UK maps the full service list.

What do tax services US/UK for families cover?

Tax services US/UK for families cover four layers: annual returns for each person, reporting of the family's accounts, gifts between family members, and estate planning. A single-country adviser usually handles the first layer for one person. A family engagement covers all four for everyone, because the layers depend on each other.

A typical household looks like this: an American parent who files a US return every year wherever they live, a British parent who files only in the UK, and children who hold both passports. Each person has a different filing position, but they share a home, bank accounts, savings and, eventually, an estate. Our tax services US/UK for families and mixed-nationality couples are built around that shared picture rather than around one taxpayer at a time.

Who in the family files what?

Each member of a US/UK family has a different set of filings. The table below shows the usual position for a family living in the UK with one American parent. Every family varies, so treat it as a starting map, not a final answer.

Family member	United States	United Kingdom	Common pressure point
American parent	Form 1040 every year on worldwide income; FBAR; Form 8938 above the thresholds; Form 8621 for UK funds	Self Assessment if they have untaxed income, such as rental, self-employment or large investment income	Foreign tax credits and timing differences between the two tax years
British (non-US) parent	Nothing, unless the couple elects to file jointly	PAYE, and Self Assessment where needed	Joint accounts and assets that appear on the American spouse's US filings
Dual-citizen children	Form 1040 once income passes the filing threshold; FBAR if their accounts exceed $10,000 in aggregate	Usually nothing while income is low; Child Benefit is claimed by a parent	Junior ISAs and children's accounts holding UK funds
The household as a whole	Gift tax returns (Form 709) for large transfers; estate tax exposure	Inheritance Tax planning, wills and lifetime gifts	Assets moved between spouses without checking both systems

American citizens living abroad file the same US returns as those living in the US. The IRS says citizens and residents abroad file income, estate and gift tax returns in the same way as those residing in the United States. A citizen whose home and main place of business are outside the US has an automatic two-month extension to 15 June to file, but IRS Publication 54 confirms that interest runs on any tax unpaid by 15 April.

The joint filing decision

The biggest single choice for a mixed-nationality couple is how the American spouse files. One route is married filing separately, which keeps the British spouse outside the US system. The other is an election to treat the non-resident spouse as a US resident so the couple can file a joint return.

The IRS explains on its non-resident spouse page that the election requires both spouses to report worldwide income for that year and every later year the choice applies, that the non-resident spouse needs a Social Security number or an ITIN (Individual Taxpayer Identification Number), and that the choice can be made only once in a lifetime. Joint filing can lower the US bill where the British spouse earns little. It can also pull the British spouse's ISAs, pension and investments into US reporting. Our guide to tax planning for a US/UK mixed couple covers the trade-offs in more depth.

How are a family's bank accounts and savings reported?

A family's UK accounts are reported to the US through the American members' filings. The FBAR (FinCEN Form 114) is required when a US person's foreign accounts together exceed $10,000 at any time in the calendar year, and Form 8938 applies above higher thresholds. A joint account with a non-American spouse still counts for the American spouse.

According to the IRS comparison of Form 8938 and FBAR requirements, a taxpayer living abroad files Form 8938 when specified foreign assets exceed $200,000 on the last day of the year or $300,000 at any time (single or married filing separately), or $400,000 and $600,000 for a joint return. Those figures matter for the joint filing decision: a joint return raises the threshold but brings the other spouse's assets into the count. Our guide to FBAR vs Form 8938 explains the differences.

Children's savings and the Junior ISA

A Junior ISA is tax-free in the UK, and GOV.UK confirms that the Junior ISA limit for the 2026 to 2027 tax year is £9,000. The US does not recognise the ISA wrapper. For a child who is a US citizen, the income is taxable in the US, and UK funds inside the account can be passive foreign investment companies (PFICs) that need Form 8621 and are taxed harshly when sold.

The answer is rarely to avoid saving. It is to choose the account owner and the investments deliberately. A cash Junior ISA, or one holding individual shares rather than funds, avoids most of the PFIC problem. Our article on ISAs and PFIC rules for US citizens goes through the options, and tax for an American baby born in the UK covers the first-year paperwork, from the Consular Report of Birth Abroad to the child's Social Security number.

Child Benefit and the US Child Tax Credit

US/UK families can often claim support from both countries, because UK Child Benefit and the US Child Tax Credit are separate systems with separate rules. The difficulty lies in claiming each one correctly.

• UK Child Benefit. HMRC claws it back through the High Income Child Benefit Charge. GOV.UK states that you repay 1% of the benefit for every £200 of income over £60,000, and all of it once income passes £80,000. The higher earner of the couple pays the charge through Self Assessment.
• US Child Tax Credit. For 2026, IRS Rev. Proc. 2025-32 sets the maximum credit at $2,200 per qualifying child, with $1,700 of it refundable. The IRS Child Tax Credit page says the child must be under 17 at the end of the year and have a valid Social Security number issued before the return's due date.

The two interact through the American parent's return. How that parent's UK earnings are relieved, through the foreign tax credit or the foreign earned income exclusion, can change how much of the US credit the family actually receives. That is a reason to model the return both ways rather than repeat last year's method.

Gifts between spouses and family members

Gifts within a US/UK family follow different rules depending on the citizenship of the giver and the recipient. Transfers between two US citizen spouses are unlimited under the marital deduction. Transfers from a US citizen to a spouse who is not a US citizen are not.

For calendar year 2026, Rev. Proc. 2025-32 excludes the first $194,000 of gifts of present interests to a non-US-citizen spouse from taxable gifts. Gifts to anyone else are excluded up to $19,000 per recipient, the same figure the IRS lists in its gift tax FAQs. Gifts above those amounts are reported on Form 709, and the same Revenue Procedure sets the 2026 basic exclusion amount for estate and lifetime gifts at $15,000,000, so most families report rather than pay.

Gifts can also run the other way. A US person who receives more than $100,000 in a tax year from a non-resident alien individual or a foreign estate reports it on Form 3520, according to the IRS page on gifts from foreign persons. That catches British grandparents who help with a house deposit, and it can catch a British spouse's large transfer to the American spouse. Our gift tax return service handles both forms.

Illustrative example: an American living in London with a British wife transfers half of a £500,000 jointly bought home into her name, a gift worth more than $194,000 at the exchange rate on the day. No US gift tax is likely to be payable because of the lifetime exclusion, but a Form 709 is due for the excess, and the couple should check the UK position before the transfer, because the same home may later count for Inheritance Tax.

How do UK Inheritance Tax and US estate tax affect a family?

UK Inheritance Tax and US estate tax can both apply to the same family estate. Since 6 April 2025, UK Inheritance Tax on worldwide assets depends on whether a person is a long-term UK resident rather than on domicile. US estate tax applies to US citizens on worldwide assets wherever they live.

GOV.UK sets the Inheritance Tax nil-rate band at £325,000, with tax at 40% above it, and a home left to children or grandchildren can raise the threshold to £500,000. Transfers to a spouse are normally exempt. The exception that matters for mixed-nationality couples is set out in HMRC's Inheritance Tax Manual at IHTM47030: where the spouse who gives is a long-term UK resident and the spouse who receives is not, the exemption is capped at the nil-rate band in force at the date of transfer.

The receiving spouse can elect to be treated as a long-term UK resident, which removes the cap. HMRC's manual at IHTM47038 says that election cannot be revoked and only lapses after 10 consecutive years of non-UK residence. That is a decision for both systems at once, which is why our US/UK trusts and estates service reviews wills, beneficiary designations and the US/UK estate tax treaty together. Our guide to UK Inheritance Tax for Americans explains the long-term resident test in detail.

What a well-scoped family engagement includes

A family engagement should list every person, every return and every recurring decision. If a proposal names only one taxpayer, it is a single return, not a family service. A full scope usually runs in this order:

1. Household map. Citizenship and residence of every family member, and where each one is heading in the next five years.
2. Filing status review. Married filing separately compared with a joint election, modelled over several years, not one.
3. Account inventory. Every UK and US account, its owner and its contents, with PFIC exposure flagged.
4. Annual returns. The US Form 1040, FBAR and Form 8938 for each American, and UK Self Assessment for whoever needs it, prepared together so that foreign tax credits line up.
5. Children's plan. Social Security numbers, Junior ISA or other savings choices, and Child Benefit claims.
6. Gift log. A running record of transfers between spouses and from relatives, with Form 709 and Form 3520 filed when they are due.
7. Estate review. Wills in each country, pensions and insurance nominations, and the Inheritance Tax spouse cap checked against US estate tax.

US/UK Cross Border Tax works as US CPAs and UK tax advisers on one team, in London, Manchester, New York and San Francisco, so that each step is checked against both systems by the same engagement.

What families get wrong

• Treating the British spouse as irrelevant to the US return. Joint accounts, a joint mortgage and transfers between spouses all reach the American spouse's US filings.
• Choosing joint filing for one good year. The election continues until it is ended and can be made only once, so a single year's saving is the wrong test.
• Opening a stocks-and-shares Junior ISA in UK funds for a US citizen child. It is a tidy UK choice that creates PFIC filings in the child's name.
• Moving the family home into one name without a gift check. A transfer to a non-citizen spouse above $194,000 in 2026 needs a Form 709, and the UK Inheritance Tax spouse cap may apply later.
• Writing wills in one country only. A UK will that ignores US estate tax, or a US will that ignores the long-term resident test, can leave the surviving spouse with the bigger bill.

How we help US/UK families

Our team prepares the American members' US returns and the UK members' Self Assessment returns in the same engagement, keeps a household account and gift log, and reviews the estate plan with both countries' rules in view. If your family has a decision coming up, such as a joint filing election, a transfer of the home, a new baby or a move, contact our US/UK team before the decision is made rather than after the return is due.