Halifax has cut the interest rate of its Help to Buy ISA from 4% to 2.5% for new customers – but if you already have one, you can breathe a sigh of relief as existing customers won't be affected by the change.

Help to Buy ISAs are a no-brainer if you're a first-time buyer saving for a mortgage deposit. You can earn up to 4% interest tax-free and then the state will add 25% free cash to help you buy a property – up to £3,000 in total.

Until today, Halifax's Help to Buy ISA paid the joint top rate of 4% tax-free, along with Santander. For more on how the Help to Buy ISA works, plus how the top picks now stack up, see our Help to Buy ISAs guide.

I've already taken out a Halifax Help to Buy ISA with an interest rate of 4% – how does this affect me?

In short, it doesn't. Halifax has confirmed that existing customers are not affected and will continue to earn 4% interest.

Has anything else changed, other than a lower interest rate for new customers?

No. One quirk of the Halifax Help to Buy ISA that remains is that to make the initial £1,200 deposit, you can pay the usual up to £200 per month in month one, and then you've 21 days from account opening to pay in the extra £1,000.

The minimum deposit remains at £1 and access is still available online, in branch or over the phone.

Why has Halifax cut the interest rate?

A Halifax spokesperson told us the bank had arrived at the decision to "align with the rest of the market".

What are the best value ISAs currently available?

We believe the following Help to Buy ISAs are currently the best available:

See the Help to Buy ISAs guide for more info.