Do we need a US will?

If you have children, a home or savings in the US, a will made under your state’s law lets you choose who inherits and who would bring up your children. For non-citizens, US estate tax works differently too, and a spouse who isn’t a US citizen doesn’t get the unlimited tax-free transfer that US citizens get.

What happens without a will

Each state has its own rules for people who die without a will (intestacy). A formula decides who inherits, and a court appoints someone to deal with the estate (probate). Two examples:

• New York: if you leave a spouse and children, your spouse gets the first $50,000 plus half of the rest, and your children share the remainder
• California: community property (most of what a married couple earns or acquires during the marriage while living there) goes to the surviving spouse. Separate property is shared with children, so your spouse may get only a half or a third of it
• Texas is also a community property state. New York, Massachusetts, DC, Illinois and Florida are not

Some assets pass outside the will altogether: joint accounts, life insurance, retirement accounts such as a 401(k) or IRA with a named beneficiary, and in some states homes and cars with a transfer-on-death deed or registration. Check every beneficiary form, because it overrides your will. See What is a 401(k)?

Making a valid will

Each state sets its own formalities. California, for example, needs the will in writing, signed by you, and signed by at least two witnesses who were present at the same time. Some people also use a revocable living trust; ask your attorney whether one suits you. Be wary of anyone selling trusts door to door or by cold call: the California Attorney General warns about living trust scams.

Your UK will

A will made in the UK can be valid in the US. California, for example, accepts a will that met the law of the place where it was signed, or of the place where you lived or were a national. The UK has a matching rule in the Wills Act 1963, so a US will is usually accepted as validly made in the UK too. Using a foreign will can still be slow, because a court may need evidence of the other country’s law.

• Many people keep a UK will for UK assets and make a US will for US assets. Ask each lawyer to limit each will to its own country, because a new will usually cancels all earlier ones
• Name executors who can act in each country
• Review both wills after a marriage, divorce, a new child or a move to another state

Naming a guardian for your children

You can name a guardian in your will to look after your children if both parents die before they turn 18. In California, a parent can nominate a guardian of the person (day-to-day care) and of the estate (money), and the court must give that choice due weight, guided by the child’s best interests. If family are in the UK, think about who could step in quickly in the US, name a back-up, and say how money for the children should be held.

Probate and small estates

Probate is the court process that confirms a will and lets the executor collect and pass on assets. Most states have a simpler route for small estates. In California, it applies where the estate is worth up to $208,850 (for deaths from 1 April 2025). Rules and limits differ in every state, so check your state court’s self-help pages.

If you can’t decide for yourself

A will only works after death. Ask your attorney about a durable power of attorney for money and an advance directive or health care proxy for medical decisions; New York, for example, has its own health care proxy form. Make US documents for life in the US. A UK lasting power of attorney is made under UK law, so ask whether it would be accepted here.

US estate tax: does the US treat you as domiciled?

For US estate tax, what matters is your domicile: living somewhere with no definite present intention of later moving away. It is not the same as tax residence for income tax. Green card holders who plan to stay are often domiciled in the US; people on a temporary visa may not be. It depends on the facts, so get advice.

The $15 million figure for 2026 comes from the tax law signed on 4 July 2025. Some assets are treated as outside the US for nonresidents, such as ordinary US bank deposits and life insurance on the nonresident’s own life.

If your spouse isn’t a US citizen

• US citizens can leave everything to a US-citizen spouse tax-free (the marital deduction). If the surviving spouse is not a US citizen, that deduction is generally not allowed, whether or not they have a green card
• The way round it is a qualified domestic trust (QDOT). At least one trustee must be a US citizen or a US company, and estate tax is charged when capital is paid out of the trust to your spouse. If the spouse later becomes a US citizen, that tax can stop
• Gifts during your lifetime to a non-citizen spouse are tax-free up to $194,000 in 2026. The ordinary annual gift exclusion to anyone else is $19,000
• Jointly owned property with a non-citizen spouse doesn’t get the special joint-ownership rule that applies between citizen spouses

State estate taxes

UK inheritance tax may still apply

Since 6 April 2025, UK inheritance tax on worldwide assets depends on long-term UK residence: UK tax resident for 10 of the previous 20 years. After you leave you stay in scope for 3 to 10 tax years, depending on how long you lived in the UK. UK property is always in scope. The UK rate is 40% above the £325,000 threshold. The UK and US have an estate tax treaty: where both countries could tax the same assets, one can give up its right or give credit for the other’s tax, with forms certified between HMRC and the IRS. See your UK tax, pension and property.