National is downplaying the cost of their tax cuts, amid calls for the party to front up.

The Council of Trade Unions is picking the policy will cost up to $8.2 billion over four years.

But National's finance spokesperson Nicola Willis says next year, the Government will collect $48 billion more in tax than it did in 2017.

She told Mike Hosking that means the $8.2 billion number the CTU has used represents less than two percent of that overall increase in tax.

She says the numbers sound big by themselves, but the policy is prudent.

LISTEN ABOVE