The bigger tax cuts would come at no extra cost to the Crown, he told 60 people attending the Otago Chamber of Commerce "meet the leaders" meeting in the Glenroy Auditorium.
National would leave unchanged the tax cuts due to come in on October 1, announced in the budget, and rather than having people wait another 18 months for the next lot, National would in government bring in tax cuts on April 1 next year and another cut in April 1, 2010.
There were two things National would change from the way the current government was operating.
Adding those two things together would give enough money for the cuts without extra costs to the Crown, he said.
The funding of the cuts would be announced in the first week of the election campaign.
Asked later whether the cuts would be funded - as suggested to the Otago Daily Times by Prime Minister Helen Clark - by stopping the tax credits to KiwiSaver and halting the payments into the New Zealand Superannuation Fund, at a combined gain of $3.5 billion, Mr Key said there would be some "modest changes" made to KiwiSaver.
Those changes would be announced soon.
He would not elaborate.
National was still planning for the election to be held on October 18, or even October 11, and the party was ready for the campaign.
The Government had been announcing appointments to various boards, indicating that the first available date for an election was November 1.
However, Mr Key said parliamentary convention was that the Government should consult about appointments in the last 100 days before an election.
But now, the Government was saying that only applied to "major appointments" and the last one was made in June.
Conventional wisdom pointed to an October 18 election, the week before the Labour Day weekend public holiday.
That meant Parliament would sit for one more week before a final week of valedictory speeches.
Parliament's sitting calendar showed the last sitting days as September 9, 10 and 11.
Miss Clark is due to visit Dunedin twice in September.
One thing Mr Key promised not to do during the campaign was to resort to personal attacks on Miss Clark or Finance Minister Michael Cullen.
He had been subjected to the attacks in Parliament for the past six to nine months.
Lately, the attacks had been taken outside of the House and into the electorate.
"I won't be doing that. I will focus on the issues that matter to New Zealand."
They included the economy, law and order, health and education - conventional election issues.
• Miss Clark will visit Dunedin twice within a week next month to officiate at various engagements.
She will be guest speaker at the Otago Daily Times Class Act function on September 11, before returning on September 16 for two events with a Chinese link.
In the morning, she will unveil the plaque commemorating the partners involved in the Dunedin Chinese garden, followed by a ceremony in the afternoon to open The Emperor's Dragons, an exhibition of Chinese treasures from the Shanghai Museum.
