The overall bank balances of anyone in KiwiSaver will be worse off under National's economic and tax plan than under Labour's policy, Labour's finance spokesman Dr Cullen said today.

National yesterday outlined a $15 billion tax cut package which incorporated some of Labour's tax cuts and would be partially funded by cutting Government's contributions to KiwiSaver accounts by $3 billion.

The tax cuts will give a worker on the average wage an extra $18 a week in their pay packet from April 1 next year.

By April 1, 2011, an average worker will be $46.50 better off, or $41 better off if they receive Working for Families.

Under Labour's package they would be $32 better off.

However, Dr Cullen argued today that this calculation failed to take into account the money that those on KiwiSaver would have had going into their bank accounts in 2011 if Labour's policy remained in place.

He said that the Government contributions to KiwiSaver accounts would outweigh the money gained from paying less tax for everyone in the scheme.

Dr Cullen calculated that someone with children and earning $50,000 would have $14.42 more in their pay packets, but if the person was in KiwiSaver the reduction of Government contributions to their savings account meant overall they were worse off by $5.57.

Someone on $30,000 in KiwiSaver would be $26.72 worse off over all.

The calculations changed if the taxpayer was not receiving anything from Working for Families, because under National there is a tax rebate for taxpayers earning between $24,000 and $50,000 who do not receive income support.

Dr Cullen calculated that someone in this position earning $50,000 would be $14.42 a week better off if they weren't in KiwiSaver, but overall $5.57 worse off if they were in KiwiSaver.

If that person was earning $30,000 they would be $8.27 better off if not in KiwiSaver, but their overall bank balance would be $11.72 worse if Labour's policy did not stay in place.

A spokesman for National leader John Key said Dr Cullen's calculations were not correct.

National said yesterday that changes to KiwiSaver that dropped the minimum contribution to 2 percent of a worker's wages would enable more people to afford the scheme.

It said the scheme was still a generous one, but was not affordable during tougher economic times.

In effect, National is proposing reducing concentrated subsidies to savers and spreading them more thinly around in tax cuts.

People concerned about the drop in employer contributions from 4 percent to 2 percent could compensate by saving their tax cut through the scheme, Mr Key said this morning.

Dr Cullen's Cabinet colleague Trevor Mallard said that Mr Key was wrong.

"John Key said that by and large people's tax cuts are larger than their KiwiSaver losses. There's not a single person, not a single person, that gets a bigger tax cut than their KiwiSaver loss," Mr Mallard said.

"It's just rubbish. and if you've got kids you're just worse off still."