The government have argued backpackers should be taxed at the same rate as those in the Seasonal Workers Program who are taxed at 15 per cent.

Treasurer Scott Morrison said lowering the superannuation rate while sticking to the 15 per cent rate would cost the budget an extra $55 million. But along with the $100 million for Landcare over the forward estimates, the hit to the budget of the compromise would be $155 million.

Earlier the government surrendered on its proposal of a 19 per cent rate which cost the budget $120 million. In total the final deal has cost $275 million.

"The rate of tax applied to the superannuation funds that are paid in by backpackers when they are in Australia, to reduce that from 95, as was the previous arrangement, down to 65. Now, that is a cost of $55 million.

Federal Greens leader Richard Di Natale has suggested members of the Left Renewal faction consider joining another party. Darrian Traynor

"That, combined with the additional commitment that is being made in relation to Landcare...these matters will be addressed in a way that the budget is preserved when I hand down my statement on MYEFO on 19 December," Mr Morrison said.

Labor leader Bill Shorten said it was not a victory as lowering the rate from 15 per cent to their 13 per cent compromise was to cost about $60 million anyway. "This is a bigger tax at a bigger cost," he said.

The agreement deals the crossbench Senators Derryn Hinch, Jacqui Lambie and Rod Culleton out of any horse trades, and allows the government to say they got their desired compromise rate of 15 per cent.

While the deal was not financially better than if the headline rate was 13 per cent, government sources said it was important to demonstrate it had other options if crossbench Senators did not stick to their commitments and wanted to push the government around and "salami slice" its policies.

The government was determined to get the matter settled by the end of Thursday otherwise the tax would revert to 32.5 per cent on January 1, 2017. Farmer argued such a rate could deter backpackers who help the horticulture industry pick crops from staying in Australia. Mr Morrison said it was about sealing the deal.

"These arrangements will ensure that we'll achieve over 70 per cent of the revenues that were set out in the budget. And in the 45th parliament, it's about getting things done," he said.