There are concerns the savings incentives in the 2007 Budget could provoke industrial strife.
The revised KiwiSaver scheme includes compulsory employer contributions, as well as tax credits for both workers and companies.
The Minister of Finance says employers could offset the cost of their contributions against wage or salary demands by their staff.
But Business New Zealand says it won't be possible for employers to negotiate on that when their participation is being made mandatory.
Chief executive Phil O'Reilly says wage demands are likely to be made in addition to KiwiSaver contributions - saddling employers with big costs.
The National Distribution Union say it is unlikely to accept Kiwisaver contributions in lieu of pay rises because its members earn too little as it is. National secretary Laila Harre says the scheme is not workable.
The Council of Trade Unions, support the plan.
Net cost small - Cullen
Finance Minister, Michael Cullen says the net cost of the revamped Kiwisaver scheme to employers is small.
Dr Cullen told Morning Report the total wage and salary bill will be 1% higher over the four years over which the 4% contribution will be phased in.
He says tradeoff with wage bargaining is a matter for negotiation, but he expects it will be taken into account.
But the National Party leader, John Key, says nothing has changed for people who can't afford to save, because they will opt out of the scheme.
Further details of the Budget are available in our Budget 2007 feature.
