The Department for Communities and Local Government is publishing details of all spending of more than £500 made during Labour's last year in power.
Communities Secretary Eric Pickles said he wanted "greater openness" and for ministers to be held to account.
His department has revealed £314m of spending, including £635,000 on taxis and cars and £310,000 on catering.
Meanwhile, £16m was spent on events, marketing, advertising and promotion in 2009/10, it has shown.
Altogether, it has published 1,900 items of expenditure for the last financial year.
On top of the £314m worth of spending by the department, there are details on £337m paid out by quangos linked to it.
Mr Pickles said the information would allow taxpayers to "go through the books and hold ministers to account".
He has already asked councils in England to publish details of all expenditure over £500 - although they will not be forced to do so.
Mr Pickles said: "This department, like the rest of Whitehall, needs to look at where every penny is going and getting this data out in the open will help that process."
He added that the figures were already showing how the department could spend more carefully, get better deals and question purchases.
All departments - apart from health and international development - have been asked to find ways to reduce costs by between 25% and 40%, as the coalition government seeks to tackle the budget deficit.
Prime Minister David Cameron said greater openness about costs would happen across Whitehall.
He added: "I can't promise that people won't make bad spending decisions in future, but I can promise that you will find out about them and that will be the best way of ensuring we get better value for money."