Buyers using the scheme can only purchase properties worth up to £450,000 in London or £250,000 elsewhere.

But since then, the national average property price has risen to a record high in February of £276,755, and the average London property has risen to £530,000.

Both are beyond the Help to Buy ISA limits.

“You can’t buy an average property using a Help to Buy ISA, and you can barely buy the average home for a first-time buyer.

“House prices have risen by a third since this type of ISA was introduced in December 2015, but the limits haven’t shifted at all.”

She suggests that anyone approaching the limits of the scheme may be better off using a Lifetime ISA

The Help to Buy ISA is closed to new applicants but current users can only contribute up to £200 per month, while Lifetime ISA users can put up to £4,000 per year into the account and earn interest tax-free as well as a 25% government bonus.

Additionally, the maximum price threshold on a Lifetime ISA purchase is £450,000 nationwide.

Coles added: “In London the difference is particularly striking, because the average home costs £80,000 more than the Help to Buy ISA scheme’s £45,000 limit, but even elsewhere in the UK, the average property costs almost 10% more than the scheme limit of £250,000.

“It means those who are relying on the government top-up to afford a property could get to the point of buying and realise they’ll breach the limit – so can’t get the bonus after all.

“The government needs to reconsider the limits on the Help to Buy LISA, and the Lifetime ISA.

“They need to be linked to house price inflation, so buyers have the security of knowing that however long they save for a property, and however house prices move in the interim, they won’t be priced out of their bonus.”