Prime Minister John Key is defending changes to KiwiSaver introduced in last week's Budget against accusations they constitute a broken election promise.
The Labour Party has accused Mr Key of making a mockery of his pledge to seek an election mandate on changes to the voluntary savings scheme as they take effect from July this year.
At the last election, National campaigned on making no changes to member entitlements this Parliamentary term.
The Government passed legislation under urgency last week to halve the maximum yearly contributions to KiwiSaver accounts, from just over $1000 to $520.
The contribution people receive from the Government will start accruing at the new amount of up to $10 a week from July, even though the actual payments will not be made until next year.
Labour finance spokesman David Cunliffe says it is a nonsense for the National-led Government to say it is seeking a mandate on the change, when it has already been legislated for.
Mr Key says Labour can make changes to the scheme if it wins the election on 26 November.
The changes to KiwiSaver were announced in the Budget on 19 May and passed into law under urgency the following day. They do not take effect until after the election.
Government contributions to KiwiSaver have been halved and employer contributions to the voluntary workplace savings scheme will no longer be tax-free.
From July 2012, the Government will put in 50c for every dollar saved to a new maximum of $521 a year, down from its current contribution of $1 for each dollar saved.
From April 2012, employer contributions will be taxed at the employee's marginal tax rate, which means less money going into the employee's scheme and more tax revenue for the Government.
In turn, employers and employees will have to contribute more each year. Their contributions rise from 2% to 3% from April 2013, and will apply to existing and new members.
The $1000 kick-start for new KiwiSaver members remains unchanged.
The Government says the changes are necessary and are part of a plan to return to surplus by the 2014-15 fiscal year.