Labor is demanding the Turnbull government include in its overhaul of childcare benefits a lift in the minimum hours it will subsidise low-income families and guarantee funding to Indigenous and mobile services.
As the Senate prepares to debate government legislation on Thursday, opposition childcare spokeswoman Kate Ellis has outlined Labor's position in a letter to Education Minister Simon Birmingham.
Labor wants the minimum hours subsidised lifted from 12 to 15 and a guarantee of ongoing funding given for 300 Indigenous and mobile childcare services.
"The need to fix the flaws in the proposed childcare package should not come as a surprise," Ms Ellis wrote to Senator Birmingham.
"It's a matter of public record that Labor has been campaigning on these changes and trying to convince the government of their merits for almost two years."
The sector had also been calling for the changes.
Under the planned changes, childcare subsidies will be rolled into a single means- and activity-tested payment.
Ms Ellis wants vulnerable and disadvantaged children and those from lower-income families guaranteed at least two days of early-childhood education.
Government figures show about one in five families earning less than $65,000 a year will lose subsidies because they do not meet the activity test of both parents working or studying at least eight hours a fortnight.