Opposition Leader Bill Shorten has set a time frame for revealing whether all small and medium-sized firms will keep a coalition tax cut.
However, he is adamant big businesses won't get the tax relief promised by the Turnbull government.
"We will finalise our policy in response after this budget (in May)," Mr Shorten told the National Press Club on Tuesday in answer to a question on the issue.
Labor opposed tax cuts for businesses with a turnover of up to $50 million when they passed the parliament last year, saying reductions should be limited to small businesses with a turnover of $2 million.
"We've made it perfectly clear for well over a year that we support the tax cut for businesses up to $2 million ... that's 87 per cent of businesses," Mr Shorten said.
"The case has not been made by this government to give companies with very large turnovers tax relief. There's been corporate tax cut reductions, they have not been handed to workers in increased wages."
Before his first major speech of the year, Finance Minister Mathias Cormann had urged the Labor leader to come clean on the tax cuts that have already been passed into law.
"Under Bill Shorten, Labor has so far put the politics of envy before policies to strengthen our economy, to create more jobs and better opportunity for Australians to get ahead," Senator Cormann said in a statement.
