The federal government is close to reaching a deal with the Australian Greens to lift the debt ceiling, Treasurer Joe Hockey says.

National gross debt is expected to exceed the present $300 billion cap by December 12 and it looks likely the Greens will side with the government to not just increase but remove the ceiling.

In return for its support, the Greens want the government to provide a detailed statement to parliament justifying any $50 billion increase in debt.

“I have no problem with greater transparency,” Mr Hockey told reporters in Canberra, after confirming that discussions with the minor party had been constructive.

“We have no problem illustrating what the debt is to be used for and how it is going to be paid for.”

The treasurer attacked the former Labor government for leaving a legacy of debt growth and opposing the coalition’s attempts to increase the debt ceiling.

While an agreement with the Greens was “not too far away”, Mr Hockey said the real concern was the national debt.