Scott Morrison says his seven-year personal income tax plan is affordable and will “run the sword” through bracket creep.

But Labor, which has signalled support for the cuts for low and middle-income earners starting on July 1, is demanding the treasurer provide a full cost breakdown of each part of the three-part plan.

The legislation for the plan, a key component of the treasurer’s third budget, was presented to parliament on Wednesday.

“Because a stronger economy delivers more revenue to the budget, we are able to responsibly afford the personal income tax plan for working Australians,” Mr Morrison told MPs on Wednesday.

Mr Morrison says the reductions will cost $140 billion over 10 years, a figure that was not included in Tuesday’s budget.

But he has repeatedly refused to give a year-by-year break down beyond the next four years during a post-budget speech and in parliamentary question time.

“We don’t provide itemised costs because they are not reliable,” he told the National Press Club during his traditional post-budget address held in Parliament House’s Great Hall.

“That is the standing practice.”

But shadow treasurer Chris Bowen questioned how the treasurer expects the parliament to vote for policies when he either doesn’t know or won’t say how much they will cost..

Mr Morrison said if Labor did not support it they should say so.

“Go out of this place, I say to the shadow treasurer, look at all of those 10 million Australians in the eye and say ‘no tax relief for you’.”

The three-stage plan that kicks off on July 1 with a low and middle-income tax offset of up to $530.

Also from July 1, the 32.5 per cent tax bracket threshold will be increased to $90,000, from $87,000, which save 210,000 people from having to pay 37 cents in the dollar due to bracket creep.

More changes are planned in 2024/25, when the government proposes abolishing the 37 per cent tax bracket altogether.

“Our seven-year tax plan runs the sword through bracket creep ensuring that those who get more hours, do overtime, get a pay rise, they get to keep more of it, rather than having to give more of it to the government,” he said

He wants the legislation – which comes at a cost of $13.4 billion over the next four years – passed as one package.

Leader of the House Christopher Pyne tried to break with tradition after Mr Morrison introduced the bill and get the parliament to debate the legislation straight away, but didn’t have sufficient voices in the house.

Opposition Leader Bill Shorten said it made no sense to be debating “a possible tax cut in the year 2024”.

“That’s two or three elections down the track,” Mr Shorten told ABC TV.