The Lifetime ISA bonus looks like free money. The IRS has questions.

It is a savings account for a first home or for later life. You can pay in up to £4,000 each year, and the government adds a 25% bonus of up to £1,000 a year. The GOV.UK guide sets out the current rules.

You must make your first payment before you turn 40. You can then keep paying in until you reach 50.

Like other ISAs, it comes in cash and stocks and shares versions. What sits inside decides most of the American consequences.

Without a charge, in three situations. You can use it towards a first home costing £450,000 or less, bought at least 12 months after your first payment. You can also withdraw from age 60, or if you are terminally ill.

Any other withdrawal carries a 25% charge. Because the charge applies to the whole amount withdrawn, it takes back more than the bonus added.

So money you pay in can end up worth less than you contributed. The GOV.UK withdrawal rules set out each condition.

As an ordinary taxable account. The American system has no concept of an ISA, so the tax-free status in Britain does nothing on a US return. Interest, dividends and gains inside it are taxable to you as they arise.

That is the same problem every ISA has for an American holder. Our guide to ISAs and the PFIC problem explains it in detail.

Because Britain charges no tax inside the wrapper, there is no British tax to credit against the American charge. The US bill therefore lands undiluted.

This catches people who assume a government-backed product must be recognised everywhere. The backing is British, and so is the relief. Nothing about it reaches the American return.

This is the genuinely awkward part. We know of no IRS guidance that addresses the bonus specifically, so its American treatment is a judgement on your facts rather than a settled rule.

The government pays the bonus into your account, and it has no American equivalent to compare it with. That uncertainty is a reason to take advice before opening one, not after years of bonuses.

Whatever position you take, apply it consistently and keep a record of each bonus payment. The provider's annual statement shows the dates and amounts.

The amounts involved are usually modest in any single year. However, they accumulate over a decade of saving, and an unresolved position on every one of them is untidy to carry forward.

Because it usually holds UK funds, and those are almost always passive foreign investment companies. The default American treatment of those funds is punitive, and each one needs its own annual form.

The IRS page for Form 8621 sets out the reporting. Our guide to Form 8621 explains who files and how many forms a portfolio produces.

The wrapper does not help, since the US ignores it. So a stocks and shares account full of index funds brings exactly the problem it would bring in a general account.

Switching an existing account from funds to cash is a disposal on the American side. So a saver who has held funds for several years should model the switch before making it, rather than assuming it is a neutral step.

Considerably, for an American saver. A cash version holds no funds, so the passive foreign investment company rules never apply. What remains is simply taxable interest on the US return.

The interest is modest on most balances, and the reporting is straightforward. Our guide to UK savings interest and US tax covers how to report that interest.

The bonus question still applies to a cash account. But removing the fund problem takes away the most expensive part of the analysis.

Probably, as part of your foreign accounts. A Lifetime ISA is a financial account held with a British provider, so it counts toward the balance tests for the FBAR and Form 8938.

Those duties depend on balances, not on tax. They apply even in a year when the account produced nothing taxable.

Our guide to Form 8938 and the FBAR explains the two regimes. Add the account to your annual list as soon as you open it.

The home route works the same for an American as for anyone else in Britain. The conveyancer arranges the withdrawal, and the money goes towards the purchase within the price limit.

Two buyers can each use their own account towards the same home. Each must meet the first-time buyer conditions for the account.

On the American side, the purchase itself is a separate matter. The withdrawal does not change the tax already due on income and gains inside the account in earlier years.

Timing matters here too. The account must have been open for a year before you buy, so a saver who starts late may miss a planned purchase date. Build that year into any plan.

You can keep the account open, but you cannot pay into an ISA while you are not UK resident. GOV.UK guidance on ISAs when you move abroad confirms the position. The bonus stops with the contributions.

The first home route centres on British property. So a saver who moves back to America and buys there may face the withdrawal charge instead.

That is a real risk for anyone whose stay in Britain may be temporary. It deserves weighing before the first payment, since the charge can outweigh several years of bonuses.

Help to Buy ISAs closed to new savers some years ago, but existing accounts can still take payments for a limited period. They also paid a 25% bonus towards a first home.

The American analysis is the same as for any other ISA. The US ignores the wrapper, the interest is taxable, and the bonus raises the same unanswered question.

If you already hold one, add it to your foreign account list. Our guide to junior ISAs and US tax shows how the same reasoning applies across the ISA family.

It depends on the goal, but a few routes avoid most of the problems. A workplace pension grows under treaty protection, which our guide to UK pensions under US rules explains.

For a home deposit, a plain savings account keeps the American side simple. You give up the bonus, but you also avoid the fund rules and the bonus uncertainty.

Where investing is the aim, our guide to US compliant investing covers the structures both systems handle well. In our practice we see the simplest option win more often than the most generous one.

None of these routes is right for everyone. The point is to compare them with the American costs included, rather than judging each product on its British merits alone.

Report it as ordinary interest on your US return, converted into dollars. The American tax year is the calendar year, so the figures come from statements covering January to December.

British providers issue statements by the UK tax year instead. So you may need two statements, or monthly figures, to rebuild the calendar-year total.

Keep the workings with your return. The same method should apply every year, which makes later years quick.

Work through this before the first payment. Once bonuses start, unwinding the account can cost more than it saved.

Write down the reasons for your decision. You will want them if your plans change.

Take an illustrative example: a 27-year-old American in Cardiff wants to buy her first flat within five years. A friend recommends a stocks and shares Lifetime ISA holding a global index fund.

In Britain, that is sensible advice. On her US return, it would mean a foreign fund with punitive default treatment, an annual Form 8621, and an unresolved question about every bonus.

She opens a cash version instead, after taking advice on the bonus. She keeps the British benefit for her deposit and avoids the fund problem entirely.

The first is assuming tax-free in Britain means tax-free everywhere. The US ignores the wrapper, so income and gains stay taxable.

The second is filling the account with UK funds. That brings the passive foreign investment company rules and a form for every fund.

The third is ignoring the chance of moving away. The withdrawal charge falls hardest on savers whose plans change.

We review savings choices for American households through our PFIC reporting service and alongside both returns. Usually the advice is short, and it is worth having before an account opens. Our UK Self Assessment service covers the British side of the same household.

If you are weighing a Lifetime ISA, send us your plans and we will set out the American position at a fixed fee agreed first. This article is general information, not personal tax advice; take advice on your own facts from a qualified adviser.