The Australian government has estimated that the cost of its First Home Saver Accounts will be $1.2 billion over five years.Last night's budget papers show that the scheme, which will commence on October 1, offers a government contribution of 17 per cent on the first $5000 a year saved in the accounts.As expected, earnings on the accounts will be taxed at 15 per cent. The government has estimated that its contributions will cost $975 million over four years and that the cost of the concessional taxation of earnings will be $125 million over that period. The Australian Taxation Office will receive $78.8 million in implementation funding.