Despite being given just an hour and a half on Thursday to read the bill and consider amendments made on the run, the Indi MP said the "honest approach" was to vote in favour of the bill.

"It was certainly pretty full on ... The very first time I saw it was when I took my seat in the chamber and it was tabled, then I walked to the table to get the bill," she said.

"I didn't enter the Parliament with the express desire to oppose the government on everything they did, so starting with opposing the government on the bill was not in my mind."

With a majority in the House of Representatives, the Coalition government does not need crossbench support to pass its legislation.

It will provide tax cuts to low and middle earners, who are earning $18,000 to $65,000 per year, which includes almost 68 per cent of Indi taxpayers - about 65,000 people.

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MPs remained at Parliament until about 9pm Thursday night, waiting for the Senate's eventual decision to also vote in favour. Dr Haines was talking to fellow North East politician, Senator Bridget McKenzie, when the bells were ringing for the Senates final vote.

Farrer MP Sussan Ley celebrated in the chamber with her government colleagues when the bill passed the Senate.

Dr Haines said income tax issues were not talked about much during Indi's election campaign. "I didn't have a strong feeling from the electorate around what the electorate would want on such a bill," she said.

"To me, the most honest approach was to support the substantive bill ... By voting with the government on this, they were immediately getting tax relief."

The tax cuts will come in three phases, with the final - and most controversial phase, questioned by MPs including Dr Haines - not due to come in until 2024, after the next election.

Indi's new MP finally met the country's leader this week, meeting with Prime Minister Scott Morrison and Treasurer Josh Frydenberg on Wednesday evening.

She also got started on a commitment to push for a national integrity commission, by seconding a motion from fellow crossbench MP Rebekha Sharkie, to be introduced to Parliament.

"Integrity is a really important issue and one the people of Indi talked about - trust and integrity," Dr Haines said.

She cannot stand in Parliament to comment on government legislation yet, until she has delivered her official first speech.

That speech has been confirmed to take place on August 1 at 11.30am.

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