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Hargreaves Lansdown* has launched a new issue of its own easy-access cash Isa paying 4.3 per cent variable, rocketing it to the top of our rates table.

This rate is only beaten by a duo of providers that boost their underlying rates for 12 months.

Trading 212* sits at the very top of our cash Isa rates table, paying 4.63 per cent. However this includes a 12-month boost of 1.03 per cent, making the underlying rate 3.6 per cent.

Below that sits app-based provider Plum*, paying 4.62 per cent. This also includes a 12-month boost, which is higher than Trading 212’s at 2.08 per cent – so your rate plummets to 2.54 per cent when the year’s up.

If you’re happy with choosing a newer, app-based provider such as Trading 212 or Plum, a bonus rate can boost your pot, provided you set a reminder to shop around for a better rate when the time comes.

However short boosts are usually restricted to new customers, so if you’ve exhausted them already it’s worth considering Hargreaves Lansdown’s new deal.

> Find out more and open an account at Hargreaves Lansdown* 

How does Hargreaves Lansdown’s cash Isa stack up?

Hargreaves Lansdown* is better known as an investing platform but it offers a range of cash savings accounts too.

It does this as a savings platform, which lets you compare multiple accounts and switch between them easily – such as when a better rate comes up.

While most of its savings accounts are provided by other banks, the 4.3 per cent cash Isa is Hargreaves Lansdown’s own account provided in partnership with Shawbrook Bank.

And although the rate is good, savers should bear some important caveats in mind.

Firstly it’s not a flexible Isa. This means that when you replace any withdrawals, your Isa allowance will be reduced. Both Trading 212's and Plum's cash Isas are flexible.

Secondly you can’t transfer directly to the cash Isa. You must transfer to the stocks and shares Isa first and then shift your money across from there.

This means you need to open a cash Isa with a minimum of £1 first, which is a problem if you’ve already maxed out your allowance.

The good news is that your money is protected for up to £120,000 under the Financial Services Compensation Scheme (FSCS). Keep in mind this level is for each bank, not account – so if you have money with Shawbrook already, any new savings will count towards that limit.

If you'd rather fix your savings for the certainty of a guaranteed rate, Coventry Building Society tops our table with a rate of 4.6 per cent. The minimum deposit is £1.

For a two-year fixed Isa, the best rate is being offered by Hodge Bank at 4.66 per cent, but the minimum deposit is £1,000.