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In this regularly updated round-up, This is Money picks our five favourite cash Isas for savers in 2025.

It is essential reading to help you choose a top savings account for your money that can also protect you from tax - and we detail the top easy access and fixed rate cash Isa deals.

This top Isa round-up has keeping our readers updated on the best savings deals since 2014 - and is kept up-to-date weekly - bookmark it for the very latest developments.

How an Isa works and why you should have one

Each year in April, savers are given a fresh Isa allowance that qualifies for tax-free interest. 

For the 2024/25 financial year, starting 6 April 2024 and ending 5 April 2025, the limit is £20,000.

You can transfer Isa money whichever way you wish between an investment account to savings account, whereas previously you could only shift it from saving to investments. 

Cash Isa rates have been rising, along with non-tax free rates. It is worth opening one to shield money away from the taxman, especially with rates moving upwards.

Isa rules state you can only contribute to one Isa per tax year.

You can also transfer an old Isa for better returns. Here's a quick guide to Isa saving.

It is possible to switch your current year's cash Isa if you move the entire amount, but it is far simpler to get your choice right in the first place.

Get an Isa to beat savings tax 

Higher rates have dragged more people into the savings tax net, meaning a cash Isa's shelter is even more valuable. 

An Isa is worth having, despite the tax-free savings interest allowance of £1,000 a year for basic rate taxpayers and £500 for higher rate taxpayers. 

If you're a basic-rate taxpayer earning 5 per cent interest, having more than £20,000 in savings will tip you into tax, for a higher-rate taxpayer that figure is £10,000 and if you are in the 45p tax bracket, you get no savings allowance at all.

You may also want to look into stocks and shares version of an Isa - how to choose the best (and cheapest) DIY investing Isa.

Our five favourite Isas:   

- Facts: £1 to open

- Transfers in: Yes

- Flexible: Yes 

 > Full details at CMC Invest*

 This is Money says: CMC Invest is the best cash Isa if you are looking for a true easy-access Isa that doesn't cut your rate for withdawing money and isn't boosted by a short-term bonus.

The cash Isa can be opened with a deposit starting from £1. It can only be opened by downloading the CMC Invest app.

There are no withdrawal restrictions, meaning customers can access their money as many times as they like without the rate dropping. It is also a flexible Isa, meaning you can withdraw money from the Isa and replace it without affecting your Isa allowance, provided you replace it within the same tax year.

Customers can transfer in an existing Isa they have with other providers.

It leans on the FSCS cover of NatWest and Qualifying Money Market Funds to protect customer deposits in its Isa up to £85,000 if it goes bust.

 - Facts: £1 to open

- Transfers in: Yes

- Flexible: Yes 

> Full details at Trading 212* 

This is Money says: Trading 212 is the next best cash Isa if you are looking for a true easy-access Isa that doesn't cut your rate for withdrawing money. 

The rate includes a 0.88 per cent bonus rate which lasts for 3 months for new customers, use this special This is Money Trading 212* link or the code TIM to secure it.

Existing customers can earn 4.5 per cent which is still higher than other providers. Interest is paid monthly.

The account can only be opened by downloading Trading 212's app. There are no limits to how many times you can withdraw your money and Trading 212 will not reduce your interest rate for accessing your money.

When you follow the link above or use the TIM code you will get the 5.38 per cent. The 0.88 per cent bonus will be added when the account is opened. 

Trading 212's Isa is a flexible Isa which is a big benefit to savers with the financial fire power to max out their Isa limit each year. 

Flexible Isas allow you to dip into your pot and, as long as you put the money back in during the same tax year, it doesn't lose its tax-free wrapper or use up any of that year's Isa allowance. 

Any cash deposited with the Trading 212 cash Isa is fully FSCS protected, as are all of the accounts in this list. Funds in the Trading 212 Isa are held in partner bank accounts with Barclays, NatWest and JPMorgan. 

Customers are able to see the percentage of their cash held at each bank is in the interest on the cash tab in the Trading 212 app.

It means if you already have money in Barclays, NatWest or JPMorgan, you'll need to be careful not to breach the £85,000 limit if you put money away with Trading 212.

- Facts: £1,000 to open

- Transfers in: Yes

- Flexible: No

> Full details at Cynergy Bank

This is Money says: Cynergy offers the best one-year fix. 

The account can be opened online and Cynergy now offers an app. There are an number of other providers offering 4.5 per cent or more for fixing for 12 months.

- Facts: £1,000 to open

- Transfers in: Yes

- Flexible: No

> Full details at Cynergy Bank 

This is Money says: Cynergy is also offering the top two year fix, with a number of different providers now offering 4.4 per cent and more. 

The best lifetime Isa

- Facts: £1 to open

- Transfers in: Yes 

- Flexible: No

> Full details at Moneybox 

This is Money says: For those aged between 18-39 who are either saving up to buy their first home or towards retirement, this is the best paying cash Lisa deal on the market. 

Save up to £4,000 each tax year and get a 25 per cent government bonus. The deal is only available via its app. 

The rate includes a 1.15 per cent fixed bonus for the first year, the underlying rate is 3.55 per cent