The Prime Minister is also planning a pre election Budget — probably in September — which will be the second this year.
Mr Sunak slashed 2p off NICs in last week’s Budget and wants to abolish the tax on wages altogether, although this is expected to take some years.
The pledge has sparked questions over where the money will come from.
The PM told The Sunday Times: “We want to end this double taxation on work. It’s unnecessarily complex.
“Our long-term ambition is to end that unfairness, to keep cutting NICs until it’s gone.
“That is the best way to reward hard work, simplify the tax system and build the kind of society that I think is right.”
He said the Tories can “make significant progress towards that goal in the next parliament”.
Mr Sunak revealed he wants to pay for the tax giveaway by curbing benefits and getting Brits back to work.
Around 2.5 million are out of work after being signed off long-term sick.
It has sent Britain’s welfare bill soaring and the PM said: “I believe strongly in a society that rewards hard work.
“I’ve talked a lot about it. It’s really important to me that we reward hard work and that’s why cutting NICs is the best way to do that.”