National has introduced an average six new taxes every term over the last nine years, but Bill English is promising there won't be any more.

The party has been attacking Labour's tax policy - or lack of it - hard over the past few weeks, calling their opponents' promise of a tax working group "vague and confused" and taking every opportunity to claim they'll introduce a bevy of new taxes.

"They seem unwilling to say just what their policy would be," Mr English told The AM Show on Monday morning.

"This matters because it's about people's livelihood, it's about a capital gains tax on their growing business."

Since taking the reins in 2008, National has introduced at least 18 new taxes and levies - six of them on petrol. Others include:

raising GST (after promising not to)

a tax on employer KiwiSaver contributions

new student loan and Family Court fees

the bright line capital gains tax on flipping houses

a border clearance levy

including GST on digital purchases

removing tax refunds for kids doing part-time work.

Mr English says changes to income tax rates have offset those changes. While he's promising another income tax cut if re-elected, there won't be any more tax hikes elsewhere.

"We don't believe you do need extra taxes to build the roads, we don't need extra taxes to build the schools we need or to assist what would be 60,000 first-home buyers into their homes.

"We built the books back into surplus from a very difficult situation, and now we're in a position... without the need for new taxes."

He said if National was planning new tax or levy hikes, he'd tell voters before the election.

"I can say that because if we were going to be doing that, we would be telling people."

The surprise GST hike was "a product of the tax reform process", Mr English says - which sounds awfully familiar to Labour's proposed tax working group.

Labour leader Jacinda Ardern has promised any suggestions the tax working group makes which Labour accepts will be in place before the 2020 election.

"There will be another election probably within 18 months of acting on that review, and if they don't agree with what we've done, I'm sure they'll tell us that."

Newshub.