ACT leader David Seymour doesn't know why his Bill to cut MPs' salaries wasn't backed.

On the first day back in Parliament yesterday, Seymour put forward a bill that would see all MPs to take a paycut, not just the Prime Minister and Ministers.

But the bill was vetoed by Grant Robertson. Last night, he told Heather du Plessis-Allan that's because the government is working on their own bill

“The government is drafting a bill to deal with this exact issue and we are adopting the normal processes of consulting with all members of parliament, instead of just one individual putting up a bill."

However, Seymour says that's not true.

He told Heather du Plessis-Allan he has not heard of such a bill, and neither has the National Party.

"I did do what he said. I sent a copy of my bill to all the parties in parliament three weeks ago, and said 'this is my best attempt, if you've got any feedback on it, please tell me'." 

Seymour says he heard back from the Greens and National, but not Labour or New Zealand First. 

He says MPs pay should be cut so that people in the public sector can do the same. 

Seymour also thinks it's better if the Bill comes from someone other than Parliament's higher powers.

"I don't think its right that the Prime Minister and her Minister cut the pay of the people that are there supposed to be asking them questions that hold them accountable."