Labor faces tough negotiations to pass its landmark tax changes even after watering down a contentious overhaul of capital gains breaks.
Both the Greens and the coalition criticised the tax changes on Friday as the government looks to the minor, left-wing party to help it ease the reforms through the Senate.
Despite the government announcing carve-outs for startups from the new capital gains regime, Opposition Leader Angus Taylor said the changes would still be toxic for Australia's prosperity and productivity.
But Greens senator Nick McKim said the changes didn't go far enough, arguing "absurdly generous" grandfathering provisions would hand $33 billion a year in tax breaks to existing investors.
Treasurer Jim Chalmers said Labor had been engaging with Senator McKim's party in the hope of getting the legislation passed.
