ISAs vs savings accounts: a complete guide to understanding your savings options

If you're trying to make the most of your money, you've likely come across both ISAs and savings accounts. Both let you put money aside and earn a return, but they work in very different ways – and choosing between them (or combining them) can make a real difference to how much you get to keep after tax.

This guide explains what ISAs are, how they differ from regular savings accounts, and helps you work out which option – or combination – makes the most sense for your situation.

What’s an ISA?

An Individual Savings Account (ISA) is a type of savings or investment account available to UK residents. The key feature is that any interest, growth, or income earned inside an ISA is completely free from tax. You don't pay Income Tax on interest, capital gains tax on investment profits, or dividend tax on income generated within an ISA.

Each tax year (6 April to 5 April), you have an annual ISA allowance (currently £20,000) which is the maximum you can pay into ISAs in total. Unused allowance can’t be carried forward to the next year, so it's a case of use it or lose it.

To be eligible for an ISA, you must be a UK resident and at least 18 years old for a Cash ISA, or 18 for a Stocks & Shares ISA or IFISA. The Lifetime ISA requires you to be between 18 and 39 at the time of opening.

What’s the difference between an ISA and a regular savings account?

The difference between a savings account and a Cash ISA isn’t how they work in practice, but how the interest is treated for tax purposes.

Interest earned on money held in a standard savings account is subject to Income Tax. However, money held in an ISA is entirely outside the tax system. There’s no limit on how much interest or growth you can earn within an ISA without facing a tax bill, and ISA income doesn’t count towards your Personal Savings Allowance (PSA) at all.

The main types of ISA

Cash ISA

A Cash ISA works similarly to a standard savings account, but the interest you earn is tax-free. You can choose between easy-access Cash ISAs, which let you withdraw money whenever you need it, or fixed rate Cash ISAs, which lock your money away for a set period in exchange for a higher interest rate. Cash ISAs are the most straightforward option and suit savers who want security and simplicity.

Stocks & Shares ISA

A Stocks & Shares ISA lets you invest in assets such as shares, funds, bonds, and investment trusts, with all growth and income sheltered from tax. Unlike a Cash ISA, your capital is at risk – the value of your investments can go down as well as up. But over the longer term, investing in the stock market has historically delivered higher returns than cash savings. A Stocks & Shares ISA is generally suited to people who are comfortable with some risk and investing for at least five years.

Innovative Finance ISA (IFISA)

An Innovative Finance ISA allows you to earn tax-free returns by lending money through peer-to-peer lending platforms. The interest rates on offer can be higher than traditional savings accounts, but the risks are also considerably greater – peer-to-peer loans are not covered by the Financial Services Compensation Scheme (FSCS), meaning you could lose money if borrowers default or the platform fails. IFISAs are generally considered suitable only for more experienced investors who understand the risks.

Lifetime ISA (LISA)

The Lifetime ISA is designed specifically to help people save for their first home or for retirement. You must be aged 18 to 39 to open one. You can save up to £4,000 per year (which counts towards your overall £20,000 ISA allowance), and the government adds a 25% bonus (up to £1,000 per year) on top of whatever you contribute. The catch is that you can only withdraw money without penalty in specific circumstances: to purchase your first home, when you reach age 60, or if you become terminally ill. Withdrawing for any other reason incurs a 25% withdrawal charge, which effectively wipes out the government bonus and then some.

Junior ISA (JISA)

A Junior ISA is a tax-free savings or investment account for children under 18. Parents or guardians can open one on a child's behalf, and anyone can contribute to it. The annual allowance for a JISA is currently £9,000 per tax year. The money can’t be withdrawn until the child turns 18, at which point the JISA automatically converts into an adult ISA. JISAs are available in both cash and stocks and shares versions.

How many ISAs can you hold?

You can hold multiple ISAs at the same time. There’s also no limit on the total number of ISA accounts you can have across your lifetime. Many people accumulate multiple ISAs over the years, particularly if they’ve opened new ones with different providers each tax year.

From the 2024/25 tax year onwards, HMRC updated their rules to allow you to open and pay into multiple ISAs of the same type in a single tax year, provided your total contributions do not exceed the annual £20,000 allowance. This gives savers more flexibility to spread their money across providers.

Cash ISA vs Stocks & Shares ISA

For most savers, the choice comes down to these two. Here’s how they compare at a high level:

The bottom line is that a Cash ISA prioritises security over growth, while a Stocks & Shares ISA accepts more volatility in exchange for the potential of higher long-term returns. Many people hold both, using a Cash ISA for money they might need in the near term, and a Stocks & Shares ISA for longer-term savings or investments.

Can I have both an ISA and a savings account?

Absolutely. There’s nothing to stop you from holding both an ISA and one or more regular savings accounts at the same time. In fact, many people find it makes sense to use both in combination, depending on what they’re saving for.

Is splitting savings between an ISA and a savings account a smart move?

For many people, yes. A common approach is to use a regular savings account – often one offering a competitive easy-access rate – for day-to-day savings and your emergency fund, while using an ISA for longer-term or larger savings where the tax benefits are most valuable.

You might also consider filling your ISA allowance first each tax year if you’re a higher rate taxpayer or anticipate your savings growing substantially. Once the allowance is used, additional savings can go into a regular account. The key is to make sure you’re using your ISA allowance before it expires at the end of each tax year, since unused allowance is permanently lost.

How flexible are ISAs vs savings accounts for withdrawals?

This varies depending on the type of account. Easy Access savings accounts and Easy Access Cash ISAs both allow you to withdraw money at any time without penalty. Fixed-rate savings bonds and fixed rate Cash ISAs typically lock your money away for a set period.

Stocks & Shares ISAs are generally accessible, but since you’re investing rather than saving, you may not want to withdraw at a time when markets are down. The Lifetime ISA is the most restrictive, with significant penalties for withdrawals outside of qualifying circumstances.

Can you transfer between ISA types?

Yes, you can transfer money from one ISA to another, including between different types of ISA. Crucially, transferring ISA money does not count as a new contribution and does not affect your annual ISA allowance, so you keep the tax-free status of money you've previously saved.

To transfer an ISA correctly, you must use the official ISA transfer process rather than simply withdrawing the money and depositing it elsewhere. If you withdraw cash and then re-deposit it, it’ll count as a new contribution and use up your current year's allowance (or, if you have no allowance left, you simply won't be able to re-add it at all).

So… is it better to have an ISA or a savings account?

The answer depends on your tax situation, how much you have saved, and your financial goals. For basic rate taxpayers with relatively modest savings, a high-interest savings account may actually offer a better headline rate than some Cash ISAs, and the PSA may be sufficient to protect your interest from tax.

However, if you’re a higher or additional rate taxpayer, if you’ve already used up your PSA, or if you’re building up significant savings over time, an ISA could be the better long-term choice. The tax-free status of an ISA becomes more valuable the more you save and the longer you save for.

It’s also worth noting that the PSA only applies to interest – not to investment gains. If you’re investing rather than saving in cash, a Stocks & Shares ISA will almost always be the more tax-efficient option compared to a general investment account.

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