HMRC has provided guidance on some key dates for when it issues payments to ISA savers. Those with a Lifetime ISA (LISA) get a 25% Government bonus on any deposits they make, meaning if you save the maximum £4,000 over a tax year, you get an extra £1,000 from HMRC.

Individuals who made deposits soon after the turn of the tax year this month may have noticed a delay in their bonus being paid into their account.

One person said the had paid in the maximum £4,000 on April 6 but their provider informed them they would not get their bonus until the end of May.

Clarifying how the system works, a HMRC spokesperson said: "Since 6th April 2018, bonuses are claimed by ISA managers on a monthly basis ('month' means the 6th of one month to the 5th of the subsequent month).

"Where the manager has received no subscriptions in the month they will make no claim. LISA managers have 14 days from the end of that period to make a claim."

The tax authority gave the example that if someone paid into their LISA on April 17, the claim should be submitted to HMRC for the bonus by May 20.

In this case, once the amount has been checked, the bonus claim will be paid to the LISA manager within 14 days of May 20.

HMRC further explained that bonuses are typically paid out between the 24th and the end of the month, depending on when the claims come in from the ISA managers.

There are some important restrictions on Lifetime ISAs, as the funds can only be used towards buying a first home, which has to be valued £450,000 or below.

You can also access the funds when you turn 60. Otherwise, there is a 25% charge to pay which will wipe away the Government bonus and part of what you initially paid in.

You have to be aged 18 or over but under the age of 40 to open a Lifetime ISA, and you can only make deposits until the age of 50.

Research from HMRC found that some LISA holders did not realise that the 25% charge would eat into some of the money they had deposited in the account.

Commenting on the research, Rachel Vahey, head of public policy at AJ Bell, said: "For those whose strategies unfold according to plan, Lifetime ISAs made it easier and quicker for them to turn their dreams of buying a house into reality.

"But others, who had to make withdrawals from their Lifetime ISA because of unforeseen changes to their circumstances, felt they had lost out because of the high withdrawal charge.

"Generally, people don't plan to make 'unauthorised' withdrawals, but they end up doing so because life doesn't always go according to the script. If they could have avoided the charge, often they would, but they haven't been able to.

"It's not right we should penalise these investors because their plans have changed and they haven't got the financial wriggle room to adapt."