Under a new scheme, announced in Chancellor George Osborne's recent Budget, for every £200 a first-time buyer saves towards a home, the Government will give them a £50 top-up.

This bonus will be available for up to a maximum £15,000 only.

So if a first-time buyer saves £12,000, the Government will add £3,000 to the pot.

Savers will be able to withdraw funds from the Isa account if they need them for another purpose, but the bonus will only be available to those using the money for a home purchase.

The Help to Buy Isa will only be available on houses up to £250,000, or £450,000 in London.

A double boost for couples

David Hollingworth, broker at London &Country Mortgages, says the maximum £3,000 top-up is available to each buyer, not just each household.

"This should give couples a double boost, taking their maximum deposit under the new scheme to £30,000."

But the Help to Buy Isa won't do much for young people wanting to get on the property ladder in a hurry.

The scheme won't start until the autumn, at which point savers can put £1,000 into the Isa.

They are then limited to saving just £200 a month.

That means they won't build the maximum £15,000 deposit until 2020, almost exactly five years away (although they can still buy a property with smaller Help to Buy savings if they wish).

Another concern is that a £15,000 deposit won't stretch far in London, so the scheme is likely to prove most useful in more affordable parts of the UK.

David Kilshaw, head of private client tax at accountants EY, says many families will still seize on the scheme.

"For those yet to buy a property, the accounts will be more attractive than virtually any other savings offering.

"It is available to those over 16 so parents who want to give their children a leg-up can contribute."

He says the sooner families start saving, the better.

"If parents contributed the maximum amount to the Isa every month when their child turned 16, they would have £15,000 for a house deposit by the age of 21."

Save tax efficiently

The Help to Buy Isa is not the only way that families can save tax efficiently for their young ones.

The Junior Isa allows them to save up to £4,000 on their behalf this financial year, with all the returns free of tax.

Your children can't touch the money until they turn 18, at which point it is theirs to use on whatever they want, whether university costs, buying their first car, or travelling the world.

They could even use it to put down a deposit on a property, although they won't get that government top-up.

Or they can carry on saving, because at this point the money can be rolled over into a fully-fledged adult Isa, retaining all its tax advantages.

Junior Isas are a gift that can grow with your child.