Individual MPs use of travel perks - such as what was used by Act leader Rodney Hide to take his fiance on an overseas holiday - will now be kept secret under new rules.

Speaker Lockwood Smith defended the changes, released this afternoon, saying that the money available for the MPs' overseas travel perk has been deducted from their collective salaries, so it is not so much a perk but something they have already paid for.

Under the Speaker's Directives, MPs can claim up to a 90 per cent rebate on international travel, based on the number of terms they have served:

One term: 25 per cent

Two terms: 50 per cent

Three terms: 75 per cent

Four terms: 90 per cent

MPs' partners can claim the same level of rebate, and the travel can be for private holidays.

Previously the quarterly release of members and ministers expenses disclosed the amount spent on this perk, and this is how Mr Hide's trips to Europe and Hawaii with his partner were exposed.

Mr Hide eventually apologised for the trips and repaid about $22,000.

Dr Smith said the use of the rebate was a private matter and individual MPs should be allowed to keep that information private.

But he said the total amount estimated by the Remuneration Authority to be used for the perk - which is deducted from MPs' salaries - should be made public, as well as the actual amount of money MPs used.

"The public has a right to know that even though members have paid for that travel out of their salaries, that the use of the travel does not exceed what is being deducted from their salaries," Dr Smith said.

The amount deducted from MPs' salaries for the 2009/10 year was $1,176,812, but MPs only used $432,989 on that. From July to September, MPs used $76,589 out of a total deduction of $294,203.

He also announced that MPs' legal costs will be released at the end of litigation.

A base MP salary is $131,000.