Malcolm Turnbull is hopeful of securing the final votes needed to pass corporate tax cuts in the final week of parliament before the federal budget.
However, Labor wants businesses to explain in detail how the proposed new 25 per cent rate will lead to more jobs, higher wages and greater investment.
The three-day sitting of both houses will kick off on Monday with the Senate debating the tax cut legislation, with only two independents Derryn Hinch and Tim Storer not having declared their hand.
Their fellow crossbencher, Liberal Democrat David Leyonhjelm, suspects Senator Hinch will wind up supporting the cuts.
But he doesn't know Senator Storer, who was sworn in only last week, well enough to have a handle on his thinking.
"But if anyone can get it across the line, (Finance Minister) Mathias Cormann can," Senator Leyonhjelm told ABC TV on Sunday.
"He is really very, very good at dealing with the crossbench and I know he is very close."
The Business Council of Australia has issued a commitment to the Senate that the tax cut would be passed on, in terms of investment, leading to jobs.
However, the federal opposition will seek the Senate's support for a short inquiry - to report the day before the budget - into the BCA's commitment.
Labor wants to see annually measurable benchmarks on wage growth and employment estimates from Australia's biggest firms and schedules of investment by state and territory.
Figures would also be sought on what investment would be made by big business if there is no change to company taxes.
The inquiry would ascertain corporate tax data, total tax paid over the past five years and the expected tax benefit from the cut.
The government is likely to bring on its university funding reforms for debate if the tax bill is passed.
Former NSW premier Kristina Keneally will deliver her first speech to the federal parliament on Tuesday.
Also in the Senate, non-government parties will seek to disallow new marine park regulations, which Labor says will allow the largest removal of area from conservation in history.
Senate reports are due on rehabilitation of mining and resources projects, transvaginal mesh implants, foreign bribery, abuse royal commission redress scheme legislation, senior public servant pay, cyberbullying and the political influence of donations.
As well, a new inquiry is expected to be set up into the prevention, investigation and prosecution of industrial deaths in Australia.