Party leader John Key will not detail by how much taxes will be cut.
Instead he is expected to outline the broad parameters of what National, if re-elected to government, would do.
In the May Budget the government allocated an extra $500 million for new spending each year over the next four years.
Mr Key and his finance spokesperson Bill English said at the time that gave them choices about what to do with the money.
They could use it on more spending, to repay debt or to cut taxes or a combination of the three.
Jonh Key is is set to announce National's tax cut plan next week. Photo: RNZ / Diego Opatowski
During the election campaign Mr Key has given the proposal more impetus, promising a tax cut announcement before election day.
That promise came just days after Mr English told reporters at the release of the pre-election economic and fiscal update that there would be no announcement to tax before the election.
What spooked Mr Key?
Was it bad publicity over Nicky Hager's Dirty Politics book and a fear National's support might take a hit?
Key now faces the prospect that next Monday's announcement will disappoint if it does not spell out tax cuts details, which he said it will not.
National also faces other problems over its tax cut proposal.
It consistently attacks Opposition spending plans, saying they are unaffordable.
But are tax cuts affordable?
Remember the much vaunted budget surpluses are yet to materialise.
The government has not yet got the extra cash in its back pocket which it can use to pay for tax cuts. The surplus the Treasury is forecasting this financial year is also paper thin and it is not a cash surplus.
National will face criticism that it is moving too quickly to cut taxes before it has the money to do so.
Tax has also been a problem for Labour ever since its leader David Cunliffe stumbled in The Press leaders' debate when Mr Key asked him whether Labour's capital gains tax would apply to family homes owned by a trust.
At the time Mr Cunliffe could not answer but later told reporters family homes owned by trusts would be exempt from the tax along with other family homes.
Cunliffe has been dogged by questions about capital gains tax all week and has had to backtrack on earlier comments.
John Key and David Cunliffe square off in the second leaders debate of the 2014 Election. Photo: Fairfax NZ
On Wednesday he said people who inherit a family home when their parents die, would have a one month period during which they could sell the property tax-free.
But a day later he changed his story, telling reporters the one month grace period was actually just an example and the time frame was yet to be decided.
His indecisiveness over the capital gains tax is unlikely to boost public confidence in the tax, particularly given it is one of Labour's key policy planks for the election.
It argues a capital gains tax would not only raise extra revenue for the government, but it would also keep rising house prices under control by taxing investors and speculators on the capital gain they make from property investments.
Labour's finance spokesperson David Parker said in turn it will help direct investment away from property and into more productive export businesses.
That argument, which is disputed by National, is being lost, however, by Mr Cunliffe's gaffes over the tax.
He does not have command of the detail of the policy in the same way as Mr Parker.
Mr Parker's command of detail was also highlighted during a debate on climate change in Auckland this week.
He argued for a toughening of the emissions trading scheme to prevent cheap international units undermining the effectiveness of the scheme here.
All political parties on the panel, except for National, agreed the current scheme is not working.
But the Green Party does not think changing the scheme is good enough. Co-leader Russel Norman argued in favour of a capital gains tax and got an unlikely ally.
Green Party Co-leader Russel Norman Photo: RNZ / Diego Opatowski
New Zealand First deputy leader Tracey Martin, who accused both Labour and National of arrogance over their approach to climate change, gave conditional support to the proposal.
Ms Martin said her party was unlikely to go as far as the Greens in promoting a carbon tax but "let's have a chat about it later on".
National's climate change issues spokesperson Tim Groser was the sole dissenting voice on the panel.
He defended National's decision to dilute the emissions trading scheme, saying it had made it clear before being elected it did not believe New Zealand should lead the way on combatting climate change.
He was also dismissive of proposals from other parties to lower transport emissions by investing more heavily in public transport.
What brought the greatest derision from Mr Groser was Internet-Mana's policy of making all public transport free.
Mr Groser told the audience - none of whom he expected to vote National - that National had invested $2 billion in public transport, particularly in commuter rail networks in Auckland and Wellington.
But he said it came at a cost, with the average trip in Auckland still being subsidised by nearly $8.
All the other parties - Labour, the Greens, Internet Mana, the Maori Party and New Zealand First - argued more could be done to get people using public transport, cycling or walking rather than using cars.
They also argued for smarter use of rail and coastal shipping to move more goods off the country's roads.
The politicians were talking about cleaning up dirty pollution, not dirty politics.
Follow Brent Edwards on Twitter @rnzgallerybrent
