Of the MPs without ministerial roles, Labour MP Chris Carter has spent the most on air travel so far this year.

Expenses for the first half of the year have been revealed. They show Te Atatu MP Chris Carter has racked up air travel bills of more than $57,000. ACT MP Sir Roger Douglas is second on the list at just over $44,000, while Maori Party MP Hone Harawira has spent over $41,500 on flights.

Of the Cabinet Ministers, Foreign Minister Murray McCully has spent $263,000 on Cabinet-approved international travel, while Trade Minister Tim Groser has spent $189,000. Prime Minister John Key's overseas travel costs for the six months were almost $83,000.

For taxis and other on-road costs, MPs in the larger electorates have racked up the bigger bills. Travelling distances and constituent commitments mean MPs such as Hone Harawira, Jacqui Dean and Sandra Goudie have bills in excess of $18,000.

The travelling commitments of Labour leader Phil Goff are also apparent. His on-road costs for the first six months of the year are almost $80,000.

More than $750,000 has been spent on MPs' accommodation in Wellington over the six month period. National has spent just over $346,000, Labour has spent almost $300,000 and the Green Party just over $60,000.

The Maori Party racked up a $32,000 bill, ACT's accommodation cost $14,000 while progressive MP Jim Anderton's costs are almost $11,000. United Future leader Peter Dunne, as a Wellington-based MP, incurred no costs.

MPs will now publicly disclose their expenses every three months, following a series of cross-party meetings on the issue.

Prime Minister John Key and Speaker Lockwood Smith says the disclosure will give a comprehensive picture of expenses paid to members by Parliamentary Services, the Office of the Clerk and Ministerial Services.

The disclosure of MPs' expenses was triggered by the outrage which erupted in Britain when it was discovered MPs had claimed for costs such as cleaning out a moat and the construction of a duck island.