Cash ISA vs stocks and shares ISA

A cash ISA is a tax-free savings account: you pay money in, it earns interest, and the money you put in cannot go down. A stocks and shares ISA is a tax-free investment account: your money is invested on the stock markets, so it can grow more over long periods but its value can also fall. Both sit inside the same £20,000 annual ISA allowance, and you can pay into both in the same tax year.

The choice between them is not about which is better in the abstract. It turns on when you need the money, how much movement you can tolerate in the meantime, and what happens if the provider fails. Cash ISA deposits are covered by the Financial Services Compensation Scheme up to £120,000 per person, per firm¹; investments in a stocks and shares ISA are not covered in the same way, because the risk of the investment itself sits with you.

One change is already scheduled. From 6 April 2027, the amount anyone under 65 can pay into a cash ISA in a tax year falls to £12,000, within an overall ISA allowance that stays at £20,000. Savers aged 65 and over keep the full £20,000 cash ISA allowance, and transfers from a stocks and shares ISA into a cash ISA stop for everyone.

Cash ISA or stocks and shares ISA: how each one works

A cash ISA works like a tax-free savings account⁶. You pay money in, the provider pays interest, and the balance is a fixed number of pounds that does not move with markets. Cash ISAs come in easy access and fixed rate forms, and the interest is free of UK tax.

A stocks and shares ISA is a tax-free investment account that lets you put money into a range of different investments⁷. The money you put in is invested on the stock markets⁶. What you hold inside it can include funds, shares, bonds and other investments, and the account is designed for money you will not need for some years.

There are four main types of adult ISA: cash ISA, stocks and shares ISA, Innovative Finance ISA and Lifetime ISA⁸. A Lifetime ISA can hold the same qualifying investments as a cash or stocks and shares ISA, so it can be either a cash-style or an investment-style account⁹. The tax-free wrapper is the same across all of them; what differs is what sits inside.

The practical difference is what you own. In a cash ISA you own a deposit with a bank or building society. In a stocks and shares ISA you own investments, and their value is set by markets rather than by the provider.

Interest or investment growth: how the tax-free returns differ

ISAs are tax exempt accounts under which any income received is free of UK tax, covering interest, dividends and capital gains⁸. In a cash ISA that means the interest is tax-free. In a stocks and shares ISA it means any dividends and returns on shares and bonds held in the ISA are tax-free¹⁰, and any cash interest, investment gains or dividends are tax-free¹¹.

The mechanism is the same, but the source of the return is not. A cash ISA pays interest at a rate the provider sets. A stocks and shares ISA produces whatever the underlying investments produce: dividends, interest from bonds, and changes in capital value, which can be positive or negative.

That distinction matters because the tax-free wrapper does not change the investment. A stocks and shares ISA lets you earn tax-free interest, but you invest your money, so the value can go down as well as up¹². The tax saving is real; the investment risk is unchanged by it.

For a saver weighing the two, the question is what the money is for. Money being held for a known cost in the near term behaves differently from money being put away for a decade or more, and the tax treatment is identical in both wrappers. The difference is entirely in how the return is generated and how certain it is.

Risk to your money and FSCS protection

A cash ISA carries less risk to your capital, within FSCS limits, than a stocks and shares ISA¹³. The money you put in cannot go down⁶. That is a statement about the deposit, not about the interest rate: the rate can change, and inflation can erode what the balance buys, but the number of pounds is fixed.

Deposit protection covers money in accounts such as current and savings accounts, including cash ISAs¹⁴. The limit is £120,000 per person, per firm¹. Where a saver holds cash ISAs with more than one bank in the same group, the limit applies across the group rather than to each brand.

A stocks and shares ISA is different. The investments may be covered under investment protection, which is a separate scheme from deposit protection and does not compensate for market losses¹⁵. If an investment falls in value, that loss is the saver's. Investment protection responds to a firm failing and mishandling assets, not to the market going down.

An Innovative Finance ISA sits outside this. It comes with higher risks than a cash ISA, and the money might not be protected by the FSCS¹⁶. Anyone comparing the three should treat the Innovative Finance ISA as the highest-risk of the group.

You can hold both types in the same tax year

A saver can subscribe to two ISAs in a tax year, one a cash ISA and the other a stocks and shares ISA, each a single component account¹⁷. In practice that means you can pay into both in the same tax year, and you can hold more than one cash ISA or more than one stocks and shares ISA at the same time¹⁸.

The £20,000 allowance is shared. You can split the £20,000 allowance across different types of ISAs, like cash ISAs and stocks and shares ISAs². The two accounts draw on one limit rather than giving you £20,000 each, and the split between them is your choice.

Not every provider offers both. Halifax, for example, says it offers both cash ISAs and stocks and shares ISAs¹⁹. Banks and building societies more often offer cash ISAs, while investment platforms and fund managers concentrate on stocks and shares ISAs, so holding the two types with different providers is common.

There is a separate rule for younger savers. A qualifying individual may subscribe to two ISAs in a tax year, one a cash ISA and the other a stocks and shares ISA, each a single component account¹³. The ISA allowance rules set out how that interacts with the adult allowance.

Cash ISA allowance for under-65s to be capped at £12,000

From 6 April 2027 the annual cash ISA subscription limit falls to £12,000 for individuals aged under 65²⁰. The overall annual ISA limit stays at £20,000, so the cash ISA limit sits within it rather than replacing it³. Savers aged 65 and over keep a £20,000 cash ISA allowance³.

The effect is that anyone under 65 who wants to use the full £20,000 allowance will need to put at least £8,000 into a stocks and shares ISA²¹. The remaining £8,000 is the portion of the overall £20,000 allowance that can go into stocks and shares ISAs or other non-cash ISAs². The stocks and shares ISA allowance itself stays at up to £20,000 a tax year².

The higher limit for older savers is deliberate. The government retained the £20,000 cash ISA limit for those aged 65 and above in recognition of the need of those approaching retirement to restructure and derisk their investments, with transfers into cash ISAs allowed for this group¹¹. Entitlement applies from the start of the tax year in which an individual turns 65⁵.

Transferring between a cash ISA and a stocks and shares ISA

Transfers between the two types are permitted at present. Regulation 19(1)(b) revoked regulation 21(4A) so as to permit transfers from stocks and shares ISAs to cash ISAs¹⁷. You can transfer between different types of ISAs, for example a cash ISA into a stocks and shares ISA or vice versa²².

You can transfer some, or all, of the money from your cash ISA from the same or previous tax years into a stocks and shares ISA and you will not lose any tax benefits on the money you transfer²³. You can also transfer existing cash ISAs and stocks and shares ISAs into a new stocks and shares ISA without affecting your allowance⁷. The how to transfer an ISA page covers the process step by step.

How long it takes depends on the type. Transfers can take up to 15 working days for cash ISAs and 30 calendar days for stocks and shares ISAs⁴. One provider says transfers could take up to 15 working days, or up to 30 days for a transfer of a stocks and shares ISA to a cash ISA²⁴. Another says most stocks and shares ISA transfers take 2 to 6 weeks, and some take longer²⁵.

For a stocks and shares ISA, you will either do an in-specie transfer, which keeps you invested throughout, or a cash transfer²⁶. Where the destination is a cash ISA, only uninvested cash can be transferred, so investments must be sold first²⁷. That means the money is out of the market during the transfer, and the sale price is whatever the market gives on the day.

Where transfers from stocks and shares to cash will stop

From April 2027, you cannot transfer a stocks and shares ISA into a cash ISA²⁸. Transfers from non-cash ISAs into cash ISAs will not be permitted⁵. The rule is set out in legislation: transfers from a stocks and shares ISA or innovative finance ISA to a cash ISA are prohibited where the account holder is below the age of 65¹¹.

For anyone aged 65 or over, the position is different. The higher cash ISA limit is retained in recognition of the need of those approaching retirement to restructure and derisk their investments, with transfers into cash ISAs allowed for this group¹¹. So the door closes for under-65s and stays open for older savers.

Transfers in the other direction continue. It will remain possible to transfer from a cash ISA to a non-cash ISA³. A saver who wants to move money from cash into investments after April 2027 can still do so.

Which is better for short-term savings, a cash ISA or a stocks and shares ISA?

For money that will be needed soon, a cash ISA keeps its value and pays interest, so the amount paid in is the amount available to take out. A stocks and shares ISA invests in the markets, so its value can fall as well as rise, and it may not have recovered by the time the money is needed. The choice turns on when the money is needed, not on which has performed better recently.

The same logic applies to an emergency fund. Money set aside for unexpected costs needs to be accessible and stable, which is why cash-style accounts are used for it²⁹. Investment accounts are designed for money that can be left alone for years.

For retirement saving, the picture is more mixed. Cash Lifetime ISAs may not be the best way to save for retirement, but stocks and shares Lifetime ISAs can be a useful complementary retirement saving vehicle for some people including the self-employed³⁰. That is a statement about the Lifetime ISA specifically, and it turns on the long horizon rather than on the wrapper.

A saver who is unsure can hold both. The £20,000 allowance can be split between cash and stocks and shares ISAs³¹, so money for the near term and money for the long term can sit in different accounts under one limit.

Can I transfer an ISA into a Junior ISA?

No. Cash ISA and Stocks and Shares ISA transfer rules allow you to transfer into any other type of ISA except Junior ISAs³². A Junior ISA can only be transferred to other Junior ISAs, and switching between a cash and a stocks and shares Junior ISA is allowed, but not to another type of ISA³³.

Within the Junior ISA family, movement between the two types is straightforward. It is possible to transfer a Junior Cash ISA into a Junior Stocks and Shares ISA, and vice versa²⁵. All or part of previous years' subscriptions, and all of the current year's subscriptions if they are being transferred, may be moved to a Junior ISA stocks and shares account for the same named child, or to a Junior ISA cash account for the same named child³⁴.

A child can hold both types. A named child may hold a cash junior ISA and a stocks and shares ISA, but only one of each type of account may be held during the childhood of the named child, though accounts may be transferred to alternative account managers³⁴. The Junior ISAs explained page covers the rules in full.

Will the overall £20,000 ISA allowance change?

No. The overall ISA allowance stays at £20,000 a tax year, across cash, stocks and shares and Innovative Finance ISAs¹¹. You can put up to £20,000 in a cash and/or stocks and shares ISA, and any income generated can grow completely tax-free³⁵. The stocks and shares ISA limit is remaining at £20,000³⁶.

What changes is the split. From April 2027 the amount under-65s can pay into cash ISAs will be cut to £12,000 a year³⁷. Anyone wanting to use their full ISA allowance will need to invest at least £8,000 in a stocks and shares ISA²¹. The £20,000 allowance can be split across different types of ISAs, such as cash ISAs and stocks and shares ISAs².

For savers aged 65 and over, the cash ISA limit remains at £20,000, so the full allowance can still go into cash²⁰. The overall limit is unchanged for everyone; only the cash portion is capped, and only for those under 65.