How much will the boost to student allowances cost?

The Government has admitted it has not prepared final costings for its just-released boost to student allowances.

On Tuesday it announced allowances and weekly loans would be boosted by $50 a week from January 1, which will affect around 130,000 students.

But the Government hasn't got a dollar figure to say how much it will cost the taxpayer. It'll only release the cost when the next part of their tertiary package, the first year fee-free policy, is announced in a couple of weeks.

A spokesman for Education Minister Chris Hipkins said that's because the two policies are connected.

"Final costings will depend on ministry advice and analysis of eligibility, and therefore the forecasted uptake, of fees-free, which will be forthcoming when that part of the work is complete in a week or two," he said.

"While we have robust estimates of the cost of the student allowance lift, official costings will be confirmed once both the first and the second policies (and their interconnectedness) are finalised," he said.

National finance spokesman Steven Joyce is calling the move "reckless"

"You don’t make such a significant Government spending decision without knowing the full cost. It is just irresponsible and reckless," he told Newshub.