A new help to buy ISA will be created, George Osborne told the House of Commons.
And a more flexible ISA giving people complete freedom to take out money and put it back in later in the year without losing their ISA tax benefits will be available this Autumn.
The Treasury said that for the Help to Buy ISA every £200 people save towards their first home, the government would put in an extra £50, up to a maximum bonus of £3,000.
He also confirmed that the annual ISA limit will go up to £15,240 in two weeks in the new tax year, from the £15,000 this year.

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People will be able to open an ISA, save up to £200 a month towards their first home, and the government will boost it by 25%. This would be equivalent to a £50 bonus for every £200 people save, up to £3,000, officials said.
On a new flexible ISA, Mr Osborne said savers will have complete freedom to take money out of an ISA and put it back in later in the year.
The official Treasury papers stated: "ISAs are being reformed so that instead of being able to put up to £15,240 in the 2015-16 tax year into an ISA in total, people can take out their money and put it back in within the same year, without losing their ISA tax benefits - as long as the repayment is made in the same financial year as the withdrawal."
Reforms have also been made to tax on savings. A new personal savings allowance will take 95% of taxpayers out of savings tax altogether, the Treasury said.

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The Treasury papers stated: "From April 2016, a tax-free allowance of £1,000 (or £500 for higher rate taxpayers) will be introduced for the interest that people earn on savings.
"If they are a basic rate taxpayer and have a total income up to £42,700 a year, they will be eligible for the £1,000 tax-free savings allowance.
"If they are a higher rate taxpayer and earn from £42,701 to £150,000, they'll be eligible for a £500 tax-free savings allowance."
Mr Osborne said: "People have already paid tax on their money when they've earned it they shouldn't have to pay a second time when they save it.
"From April next year the first £1,000 of the interest you earn on your savings will be completely tax-free."‪

On the help to buy ISAs the Treasury released the following summary to explain how it will work:

• new accounts will be available for 4 years, but once you have opened an account there's no limit on how you long you can save for
• accounts will be available through banks and building societies from Autumn 2015
• you can make an initial deposit of £1,000 when you open the account – in addition to normal monthly savings
• there is no minimum monthly deposit – but you can save up to £200 a month
• accounts are limited to one per person rather than one per home – so those buying together can both receive a bonus
• only available to individuals who are 16 and over
• the bonus is available to first time buyers purchasing UK properties
• minimum bonus size of £400 per person
• maximum bonus size of £3,000 per person
• the bonus will be available on home purchases of up to £450,000 in London and up to £250,000 outside London
• the bonus will be paid when you buy your first home