Labor and some crossbench MPs will arrive in Canberra next Monday despite the Turnbull government postponing the lower house sitting by a week.
It is understood the shadow ministry and Labor caucus will meet, while the Greens' Adam Bandt and independent Bob Katter have also confirmed they will turn up.
Leader of the House Christopher Pyne said on Monday the decision to sit from December 4 instead of November 27 had been made because the Senate, which will sit, is unlikely to finish debating same-sex marriage laws until November 30.
The bill will then pass to the lower house for debate.
Labor leader Bill Shorten says Mr Turnbull is a "coward" and running scared from the parliament, as the coalition was two MPs short due to by-election campaigns.
"Mr Turnbull should remember the parliament does not belong to him or the government - it belongs to the people of Australia," Mr Shorten said.
In theory the lower house could sit, as section 39 of the constitution provides for a quorum being at least one-third of all members, but the clerk of the House of Representatives says no one outside the government can force a sitting of parliament.
Mr Pyne says Labor's "political stunt" will cost $787,000 to fly its MPs to Canberra when parliament isn't sitting.
Former Nationals leader Barnaby Joyce is expected to be returned at the December 2 by-election in his NSW seat of New England and would not be available for a parliamentary sitting week starting on November 27.
As well, there are fears the government could lose the seat of Bennelong to Labor, after the opposition preselected former NSW premier Kristina Keneally to run against Liberal John Alexander in the December 16 by-election.
A renewed push for a banking commission of inquiry is also weighing heavily on Mr Turnbull, as coalition backbenchers move closer to getting the numbers for what could be an embarrassing defeat for the government which opposes such an inquiry.
Mr Pyne says the decision has nothing to do with numbers on the floor of parliament, as he did not expect an official result in the New England by-election until later in December.
In any case, the government has the support of crossbench MPs Cathy McGowan and Rebekha Sharkie for confidence and supply.
He says the government wanted not only to pass the same-sex marriage laws, but deal with the MP citizenship issue before year's end.
"That is the commitment we have made and that is what the Australian people expect," Mr Pyne said.
The lower house will resume on December 4 and will immediately pass a resolution setting a deadline of 8pm on December 5 for citizen disclosures.
Then it will move onto debating and passing the marriage equality bill and any amendments.
Any referrals to the High Court resulting from members' disclosures will be debated after the passage of the marriage equality bill.
Mr Pyne says MPs should be prepared to sit for some, or all, of the second week starting December 11.
Independent MP Bob Katter says he will be coming to Canberra next week and lobbying other MPs for the lower house to sit as scheduled.
Mr Bandt says parliament should also discuss the banking inquiry and penalty rates next week.
