Cash ISA Limit Calculator

£12,000 a year if you are under 65, and £20,000 if you are 65 or over. The overall ISA allowance is unchanged at £20,000, so an under-65 saver can still shelter the full amount — but £8,000 of it has to go into a stocks and shares ISA, an innovative finance ISA or a Lifetime ISA rather than into cash. The higher entitlement for older savers applies from the tax year in which you turn 65.

On 6 April 2027, the first day of the 2027/28 tax year. The 2026/27 tax year runs entirely under the current rules, so anyone under 65 can still subscribe up to £20,000 to a cash ISA until 5 April 2027. HMRC published the draft Individual Savings Account (Amendment) Regulations 2026 for technical consultation in July 2026, with comments closing on 2 August 2026, so the fine detail could still shift before the regulations are laid.

No. The £12,000 figure caps new subscriptions in a tax year, not accumulated balances. Everything already inside a cash ISA from earlier years stays sheltered from UK tax indefinitely, keeps earning interest tax-free, and does not need to be moved, converted or restructured. A saver with £180,000 built up over a decade keeps all of it. This is the single most misunderstood point about the reform and the source of most of the unnecessary alarm.

If you are under 65, already hold the cash, and intended to keep it in savings, then yes. Subscribing the full £20,000 before 5 April 2027 locks in £8,000 more permanently sheltered cash than any later year will allow, and it costs nothing to do. For a couple that is £40,000 rather than £24,000. It is not a reason to sell investments or to hold more cash than your circumstances justify — the benefit is only worth having if the cash was going to exist anyway.

A flat-rate charge on any interest or alternative finance return paid on cash held inside a stocks and shares ISA or innovative finance ISA, introduced to stop under-65s using an investment wrapper as a substitute cash ISA. It is collected from the ISA manager, who accounts for it to HMRC, rather than assessed on you personally. At 22% it sits just above the basic rate, so it removes the arbitrage for basic-rate savers while leaving higher and additional-rate taxpayers marginally better off than in an unwrapped account.

Not if you are under 65, once the new rules take effect. Transfers from a stocks and shares ISA or an innovative finance ISA into a cash ISA are prohibited for under-65s, although transfers in the opposite direction — cash into stocks and shares — remain permitted. Savers aged 65 and over are not caught by the restriction. The asymmetry is deliberate: the policy intent is to move money from deposits into investment rather than the other way round.

The Personal Savings Allowance gives basic-rate taxpayers £1,000 of interest tax-free, higher-rate taxpayers £500, and additional-rate taxpayers nothing at all. Above that, interest is taxed at your marginal rate of 20%, 40% or 45%. There is also a starting rate for savings — a £5,000 band taxed at 0% sitting above the £12,570 personal allowance, giving a £17,570 threshold — but it is withdrawn pound for pound as other income rises, so it helps only those with low earned income.

The draft regulations define the category narrowly, treating money market funds as cash-like while shares, bonds, investment trusts and exchange-traded funds are not. A stocks and shares ISA whose portfolio consists entirely of cash-like assets becomes a non-qualifying investment, which is a separate restriction from the 22% interest charge. Anyone whose strategy involves parking in a money market fund for long periods should read the final regulations closely when they are laid.

No. The overall annual ISA allowance stays at £20,000 for everyone. What changes is the composition: an under-65 saver can direct a maximum of £12,000 of it into cash, with the balance available only through a stocks and shares ISA, an innovative finance ISA or a Lifetime ISA within that account's own £4,000 annual cap. Nobody loses allowance; some people lose the freedom to hold all of it as deposits.

No, and this is the point most commentary misses. The United States taxes its citizens on worldwide income and does not recognise the ISA wrapper, with no treaty article protecting it. Cash ISA interest is ordinary income on Form 1040 at your marginal US rate in the year it arises, whether or not you withdraw it. A foreign tax credit is available for UK tax actually paid on the same interest — but since the ISA pays no UK tax, there is nothing to credit, and the US tax stands in full.

Usually not. Most UK funds and investment trusts held inside a stocks and shares ISA are Passive Foreign Investment Companies under US law, taxed under the punitive excess distribution rules with a non-deductible interest charge and reported on Form 8621, often one form per fund per year. The wrapper the reform steers savers towards is therefore the most US-toxic place a US person could put the money. Individual shares, US-domiciled holdings in a taxable account, or a UK pension protected by the treaty are generally better routes.

Probably not. A foreign levy generally has to be an income tax and has to be your own legal liability before it becomes creditable, and the 22% is charged on the ISA manager in respect of interest paid on cash within the wrapper. That sits awkwardly against both tests. Until the final regulations and any HMRC guidance settle the point, the prudent assumption for a US person is that the charge reduces the interest credited to your account without producing any US offset — an economic cost with no relief on either side.

Yes, if you are a US person. A cash ISA is a foreign financial account and counts towards the $10,000 aggregate high-balance threshold that triggers FinCEN Form 114, the FBAR. A stocks and shares ISA counts too, and each fund inside it is potentially a separate PFIC reportable on Form 8621. Depending on your totals, Form 8938 under FATCA may also apply, with thresholds that are considerably higher for taxpayers living abroad than for those in the States. None of this depends on whether you withdrew anything.

It applies the announced £12,000 and £20,000 cash ISA limits, the 2026/27 Personal Savings Allowance of £1,000, £500 or nil, UK savings tax at 20%, 40% or 45%, and the 22% charge on cash inside a stocks and shares ISA, together with a flat marginal US rate for US persons. It assumes a single blended interest rate, a full tax year of holding, and that your band does not change. It does not model the starting rate for savings, Lifetime ISA bonuses, PFIC calculations, or state tax. Use it as a planning baseline rather than a filing figure.