Research from OneFamily suggests this flaw has delayed 45,000 first-time buyers from getting on the housing ladder.

Under the Help to Buy ISA scheme, first-time buyers can save up to £200 a month and receive a government bonus of 25%. However, the bonus is only paid out after completion so cannot be used towards the initial exchange deposit.

The mortgage lender receives the government bonus after completion, and the bonus is added to the mortgage deposit reducing the amount you need to borrow.

OneFamily claims this loophole has delayed a quarter of the purchases made using the Help to Buy ISA – an estimated 45,000 purchases in total – as first-time buyers realise they have a major hole in their finances.

One in six buyers end up borrowing money from friends and family to cover the deposit gap, according to the findings.

According to OneFamily, more unsuspecting first-time buyers could fall victim to the same catch.

Nearly seven in 10 people planning to buy their first home in the next three years mistakenly believe they can put the cash saved in a Help to Buy ISA towards the exchange deposit.

This means around 700,000 savers could be caught short by up to £3,000 when they are ready to buy and may have to delay their property purchase as a result.

Understanding of the Help to Buy ISA is stubbornly low. Among all potential first-time buyers, two in five (41%) wrongly believed you can use the Help to Buy ISA on any mortgage – but it can only be used to buy a home worth up to £250,000 (or under £450,000 in London).

Plus six in 10 (61%) don’t know whether the Help To Buy ISA or Lifetime ISA allows them to save more.

The Lifetime ISA is another option for homebuyers. Introduced in 2017, it allows people aged 18-39 to save up to £4,000 a year for their first home (or retirement) and they receive a maximum £1,000 bonus from the government.