Cash ISA vs Stocks and Shares ISA
A cash ISA and a stocks and shares ISA share one £20,000 yearly allowance and the same tax-free treatment, but a cash ISA holds savings that cannot fall while a stocks and shares ISA holds investments that can. From 6 April 2027 under-65s will be able to put only £12,000 of it into cash.
A cash ISA and a stocks and shares ISA are two ways to use the same yearly allowance: one holds savings that cannot fall, the other holds funds and shares that can grow faster and can also lose value. Both are free of UK tax on what they earn, so the choice is about risk and timing rather than tax.
What each one is
A cash ISA is a savings account inside the ISA wrapper. GOV.UK lists bank and building society savings and some National Savings and Investments products as what it can hold. Interest on that cash is not taxed (GOV.UK, How ISAs work, read 26 Sep 2026).
A stocks and shares ISA is an investment account inside the same wrapper. It can hold company shares, unit trusts and investment funds, corporate bonds, government bonds and long-term asset funds, and income and gains inside it are not taxed either. The stocks and shares ISA page covers that side in depth, including the fees that still apply.
Both draw on one allowance. In the 2026 to 2027 tax year the maximum across all your ISAs is £20,000, and the tax year runs from 6 April to 5 April. GOV.UK says you can put the whole amount in one account or split it across several, so a saver can hold both types in the same year.
Where they differ
What can happen to the balance. A cash ISA balance grows by the interest paid and does not move with markets. A stocks and shares ISA moves with markets, and a bad year can leave it below what went in, whereas the cash balance never shows a loss in pounds.
What beats inflation. Rather than losing pounds, cash tends to lose buying power. Bank of England Bank Rate, which is a benchmark and not a rate any ISA pays, averaged less than CPI inflation in 15 of the 17 tax years from 2008 to 2009 through 2024 to 2025. Investments have no promised return at all, but they are not tied to the policy rate either.
How long the money can stay put. Both allow withdrawals at any time without losing the tax benefits, per GOV.UK, though a provider can set its own terms or charges. The difference is that selling investments after a fall locks the loss in, while taking cash out costs nothing but future interest.
How much each one can take from April 2027. Today either type can take the full £20,000. Under the policy paper, savers under 65 will be limited to £12,000 a year in cash from 6 April 2027, while the stocks and shares side can still take the whole allowance.
What changes on 6 April 2027
HMRC set the change out in a policy paper, Cash Individual Savings Account (ISA) limit reduction, published 17 September 2026 (read 26 Sep 2026). The paper describes regulations that will be amended, so everything in this section is described as the paper describes it and should be rechecked when the amending regulations are made.
The cash limit. The paper says the measure will reduce the annual cash ISA subscription limit to £12,000 for individuals aged under 65 from 6 April 2027, within the overall ISA subscription limit of £20,000. For those aged 65 or over, the cash limit will remain at £20,000.
The rules to stop money being routed around the cap. The paper lists restrictions on transfers from stocks and shares ISAs and innovative finance ISAs into cash ISAs, a 22% flat rate charge on interest paid on cash held in those non-cash ISAs, and rules relating to money market funds. The paper states the measure will have effect from 6 April 2027.
Who it reaches. By HMRC’s own count in the same paper, 78% of cash ISA subscribers aged under 65 put in less than £12,000 in 2022 to 2023, and 22% put in more.
A worked example, on the paper’s figures. A 40-year-old who wants to shelter the full £20,000 in 2027 to 2028 could put at most £12,000 into cash, and the other £8,000 would have to go into a stocks and shares or innovative finance ISA, or stay outside the wrapper.
If that saver instead parked £8,000 as cash inside a stocks and shares ISA and it earned a hypothetical £300 of interest, a 22% charge would take £66 of it.
Which one to use: cash ISA or stocks and shares ISA?
Use a cash ISA when the money has a date on it within the next few years. A house deposit, a car or an emergency fund needs to be there in full on the day, and a balance that cannot fall is worth more for that job than a higher expected return.
Use a stocks and shares ISA when the money can stay invested for five years or more. Over long stretches the inflation gap in the data below is the bigger risk, and time horizon covers why a longer wait makes the swings easier to sit through.
Use both when the money has both jobs. The allowance splits freely, so a reserve in cash and the rest invested is a normal pattern rather than a compromise. From April 2027, anyone under 65 who wants more than £12,000 a year sheltered will be pushed into that split anyway.
At 65 and over, lean on cash more freely when you need to. The paper keeps the full £20,000 cash limit for that age group, so an older saver who wants the certainty of cash will not face the cap that younger savers will.
Moving money between the two
A transfer keeps the allowance; a withdrawal spends it. GOV.UK says you can move all or part of an ISA to another provider at any time, into a different type of ISA or the same type, using the new provider’s transfer form. If you withdraw the money without doing this, you will not be able to reinvest that part of your tax-free allowance again.
Transfers have deadlines. Cash-to-cash transfers should take no longer than 15 working days, and other types of transfer 30 calendar days, per the same GOV.UK page.
Flexible ISAs soften the withdrawal rule. If your ISA is flexible, cash taken out can go back in during the same tax year without using fresh allowance. Your provider says whether it is.
From April 2027 the route from investments back to cash narrows. The policy paper lists restrictions on transfers from stocks and shares ISAs into cash ISAs without spelling out the detail on that page, so check the rules in force before planning a move in that direction.
The original data
These figures come from HMRC’s ISA statistics published 16 September 2026, with Bank of England Bank Rate and ONS consumer price inflation read the same day. The figures for 2024 to 2025 are provisional.
Savers put £2.57 into cash for every £1 into stocks and shares. In 2024 to 2025, £95.6 billion went into cash ISAs and £37.2 billion into stocks and shares ISAs: 70.4% and 27.4% of all adult ISA money. That was 10.71 million cash ISA accounts at an average of £8,922, against 4.89 million stocks and shares accounts at an average of £7,602.
Cash took more than stocks and shares in 16 of the 17 tax years since 2008 to 2009. The exception was 2021 to 2022, when Bank Rate averaged 0.20%: cash fell to £30.9 billion and stocks and shares took £34.2 billion, leaving cash at its lowest share of all adult ISA money, 46.2%.
The 15-of-17 count sets each tax year’s average Bank Rate against the average of ONS’s twelve monthly CPI annual rates for April to March. Measured instead by the March-to-March change in the CPI index, it is 13 of 17, so the direction holds but the exact count depends on the method.
By 2024 to 2025 Bank Rate averaged 4.94%, cash money had risen to 3.09 times its 2021 to 2022 level, and stocks and shares money only 1.09 times.
What that cash earned against prices. £1,000 compounded daily at Bank Rate from 6 April 2008 to 5 April 2025, with no tax taken, as inside an ISA, grows to £1,243, while the ONS CPI index (series D7BT) rose 63.7% from March 2008 to March 2025. In March 2008 prices that £1,243 is worth £760, a fall of 24.0% in buying power.
Bank Rate stood at 3.75% on 24 September 2026. A cash ISA can pay more or less than Bank Rate, so this is a benchmark, not an account’s record, and no comparable official series for UK share returns was available to set beside it.
Who chooses which. Of 13.05 million adults who paid into an ISA in 2023 to 2024, 68.7% used cash only, and 31.3% put at least some money into stocks and shares (7.5% used both). Cash-only was least common at ages 30 to 32, at 62.3%, and rose in each older age group from 51 to 53 onward, reaching 82.9% at 81 and over.
Where the money sits. At 5 April 2025 cash ISAs held £419.9 billion and stocks and shares ISAs £531.5 billion, so cash was 44.1% of the value but 70.4% of the latest year’s new money. That gap has several causes, including market growth, withdrawals and different mixes in past years, so it is not a return figure.
Inside stocks and shares ISAs, £22.4 billion (4.2%) was cash on deposit, up from £5.2 billion at 5 April 2012: that is the kind of balance the planned 22% charge on interest would reach.
The full tables are published as CSVs: cash vs stocks and shares subscriptions with Bank Rate and CPI by year, subscribers by age and market values.
When it fails
Cash fails slowly. Holding long-term money in a cash ISA does not show a loss in pounds, which is why it feels safe, but in 15 of the last 17 tax years the policy rate ran below inflation. The £1,000 benchmark above lost 24.0% of its buying power over seventeen years while its balance only ever went up.
Stocks and shares fail at the wrong moment. An investment ISA holding next year’s house deposit can be down when the deposit is due, and selling then turns a paper fall into a real one. The fix is matching the account to the date, not picking the account with the better recent record.
Withdrawing to switch uses allowance twice. Taking money out of one type and paying it into the other counts as a new subscription unless it goes through a transfer form, so it eats into that year’s £20,000.
Parking cash inside a stocks and shares ISA to dodge the new cap will cost more from April 2027. On the policy paper’s description, interest on that cash would carry the 22% charge, and transfers back into cash would be restricted, so the workaround gives up part of what the wrapper was for.
Related
The stocks and shares ISA page covers the investing side, its fees and the allowance rules in full. Inflation and savings explains why a cash balance that never falls can still lose value, and the inflation-adjusted return calculator runs that arithmetic on your own numbers.
Money market funds covers the cash-like funds the April 2027 rules also mention. For the ISA set against US accounts, see taxable account vs stocks and shares ISA and 401(k) vs stocks and shares ISA, and the retirement-account versions in Roth IRA vs stocks and shares ISA, traditional IRA vs stocks and shares ISA, Roth 401(k) vs stocks and shares ISA and HSA investing vs stocks and shares ISA.
Decide by the date the money is needed, not by the interest rate on offer this month. Cash for anything due within a few years, invested for anything that can wait five or more, and check the cash part fits under £12,000 once the April 2027 limit starts.
— Michael Whitman
This page is educational, not financial advice. Test every idea on your own charts before risking money.