MPs' generous superannuation schemes will not be cut, despite Government plans to slash the subsidies paid to KiwiSaver accounts.

Finance Minister Bill English, who was elected in 1990 and so qualifies for the gold-plated pre-1992 scheme, said the Government had not considered cutting politicians' entitlements.

He said MPs' super "has been reduced quite significantly over the years to the point where I think MPs who come into Parliament in recent elections get pretty much the same deal as everybody else".

Since 1992, MPs have been entitled to a subsidy of up to 20 per cent of their salary, receiving $2.50 for every dollar they put in. Those elected before 1992 receive a subsidy equal to 23 per cent of their gross salary.

Asked why taxpayers should subsidise MPs up to 20 per cent when he was winding back KiwiSaver subsidies, Mr English said they were different schemes.

"The MPs' scheme has been wound down over the last 20 years to something that is pretty similar to what everyone has available to them. In fact, I think a number of MPs are probably members of KiwiSaver."

Prime Minister John Key has said the May 19 Budget will include plans to reduce, but not scrap, the KiwiSaver member tax credit, worth up to $20 a week. It will force employers and employees to increase their minimum 2 per cent contributions to make up the difference. The tax credit is budgeted to cost the Government $880 million this year.

Labour finance spokesman David Cunliffe said the move undermined confidence in the scheme, which has more than 1.7 million members.

He said Labour would release its savings policy later. "That does not mean we will not restore the member tax credit. But we will have to make a judgment after seeing the Budget books."

Labour would aim to "build up, broaden and grow KiwiSaver".