QANTAS, Woolworths and other major corporations will face a grilling today over their claim they will invest more in Australia if a massive cut to the corporate tax rate is passed.

The Business Council of Australia will also face questions at a Senate inquiry in Sydney today about the letter it sent to all senators last month urging them to pass the Turnbull Government’s tax cuts.

Other corporate signatories to the letter including BHP, Energy Australia, MYOB and Fortescue Metals Group will face further questioning on Thursday about the claim, with hearings likely to focus on a draft of the letter made public last month which revealed their final commitment was watered down.

In the final letter, the corporations wrote: “We believe that a reduction in the corporate tax rate, as proposed through the Government’s enterprise tax plan, is urgent and vital to keep Australia competitive.”

“If the Senate passes this important legislation we, as some of the nation’s largest employers, commit to invest more in Australia which will lead to employing more Australians and therefore stronger wage growth as the tax cut takes effect.”

The draft version committed the corporations to create more jobs in cities, suburbs, towns and regional Australia and invest in more Australian projects and ideas.

It also stated the tax cuts would allow the corporations to be “in a stronger position to avoid offshoring of jobs” and “be able to increase wages when the conditions are right”.

They also pledged to “pay our tax and show our commitment by signing the ATO’s tax transparency standard”.

The government delayed putting legislation that would lower the tax rate to 25 per cent for all business to a vote in the upper house just before Easter, admitting it didn’t have the numbers.

Crossbench senators Tim Storer and Derryn Hinch were the key votes the government needed to secure.

Senator Storer has ruled out supporting the bill in its current form but told ABC radio today he was still negotiating with the government and would keep an eye on what was in the budget.

He said he would not be horsetrading for his vote but would review legislation on its merits.

Senator Storer also ruled out calling for Australia’s banks to be denied the tax cuts as penalty for misconduct that was being exposed in the royal commission.

One Nation leader Pauline Hanson has called for that carve out but this morning insisted she still supported cutting the corporate tax rate.

“I believe now, having looked at it, and looked at what’s happening in America, that corporate tax cuts are a necessity here,” she told the ABC.

Senator Hanson said she had never claimed the tax cuts would lead to higher wages for workers but said they would prevent Australian companies from closing or shifting overseas.