Centre Alliance is confident it has secured a deal with the Morrison government on a plan to bring down gas prices in exchange for voting for the $158 billion tax package.

The tax relief plan would deliver $1080 tax cuts for 10 million Australians now and legislate a 30 per cent top tax rate for 94 per cent of Australian workers from 2024.

As Parliament returns this week for the first time since the May 18 election, the entire tax package – including tax cuts for wealthier workers – could become law as early as Thursday.

While the crossbench senators are still describing the deal as “close” they concede it’s only a matter of detail now with the substances – including limits on gas exports – largely agreed.

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Centre Alliance Senator Rex Patrick told The New Daily he was confident the tax cuts could be voted on this week.

The price of the agreement is a range of measures, including limits on future gas exports and greater transparency on existing deals.

“They were alive to the issue of gas prices. They will announce those over the next couple of months,” Senator Patrick said.

“(Resources Minister) Matt Canavan has already foreshadowed that the government is looking at a gas reservation policy. That would be prospective.

“I’ve talked about how you deal with current projects.

“We’re close.”

"The PM swore black & blue that millions of Australians would have their first round of tax cuts by today, June 30. Well, today has arrived & they haven't been delivered. Do you owe all of those tax payers an apology for the broken promise?" @annabelcrabb@Birmo #Insiders pic.twitter.com/SkM3GPUBa8

— Insiders ABC (@InsidersABC) June 30, 2019

Mr Patrick said the government had to wrestle with how any limits on gas exports would comply with free-trade obligations so they were not “unlawful”.

“We have to comply with world trade obligations. That constrains the government in terms of what it can do,” he said.

“We will meet Mathias Cormann either Monday or Tuesday to try and finalise what we have been doing remotely.

“Do I think we will end up with any roadblocks? I can’t see any. I think we can get there, but the devil is in the detail.”

Senator Patrick said he was not going to speak for Tasmanian Senator Jacqui Lambie, but she supported the gas reforms.

“She’s already indicated publicly she’s supporting what we are doing on gas. She was also concerned about gas prices,” he said.

Labor has yet to announce a final position on the Stage 3 tax cuts.

Independent costings suggest that one-third of the $95 billion in tax relief will go to the top 10 per cent of income earners.

“Bizarrely I read in the papers today they were waiting to see what we do,” Senator Patrick said.

“We’ve never been completely comfortable with Stage 3. But we recognise the government is not going to split the bill.”

Simon Birmingham. Photo: AAP

Earlier, Trade Minister Simon Birmingham said Labor’s refusal to back tax relief was a “stain on the Labor Party”.

“Labor ought to come clean tomorrow and make sure they declare that ultimately they will pass this tax relief agenda because the failure to deliver tax relief for hard-working Australians will be a stain that will haunt Labor and Anthony Albanese all the way to the next election if they block this agenda,” Senator Birmingham said.

Treasurer Josh Frydenberg urged Labor leader Anthony Albanese to follow the advice of ALP frontbencher Joel Fitzgibbon and wave through the tax cuts.

“Anthony Albanese should drop Bill Shorten’s losing strategy, cut his losses and stop denying the Australian people the tax cuts they voted for,” he said.