Speaker Lockwood Smith will decide tonight whether to abolish MPs' travel perks - but a wholesale scrapping is increasingly unlikely as some MPs argue to keep a limited discount for work trips.

Dr Smith has not yet commented on the Prime Minister's request, saying he first had to meet the Parliamentary Services Commission - a committee of MPs which meets in secret to consider MPs' entitlements.

That meeting is scheduled for tonight.

Prime Minister John Key asked the Speaker to abolish the perk this week following Pansy Wong's resignation as minister over her husband's use of it on a trip to China where he also conducted business.

Mr Key proposed the independent Remuneration Authority be asked to abolish it and make any other changes required.

While there is broad consensus over scrapping the perks for holidays, Labour MPs at least are expected to argue in favour of retaining some funding for MPs to go on trips related to their parliamentary work, such as meeting MPs overseas or attending conferences. If their wish is granted, it is likely to make any compensatory salary increase lower than if the perk is completely wiped.

Labour leader Phil Goff has made it clear he sees the use of the rebates for holidays as unjustifiable but legitimate work-related trips were important. Opposition MPs and backbenchers are limited to official parliamentary delegations and there are few opportunities to take trips of their own initiative.

The Speaker has previously said allowing opposition MPs the travel rebates was important for democracy and changed the rules for the perk to specifically say it could be used for parliamentary purposes.

Recently several Labour MPs have used their rebates for such trips including Mr Goff and Lianne Dalziel to Australia and Clayton Cosgrove, George Hawkins and Ross Robertson to China. Act MP Sir Roger Douglas has also used it for trips to the United Kingdom and Australia to address conferences and meet politicians.

Sir Doug Kidd's review this year also recommended scrapping the holidays perk but retaining entitlements to allow MPs to go on work-related trips.

It suggested analysing the use of the rebates in recent years to calculate the ratio of holiday to work travel. If some level of rebate was retained, any compensatory salary increase would be based on the level of the holidays travel alone rather than the full $9800 value of the perk.

Green co-leader Metiria Turei will also ask the commission to back her call for an independent body to review and set MPs' entitlements. She has accused Mr Key of wasting time by waiting for a Law Commission report on the issue, expected by the end of the year.