Govt still working on GST carve-up reply

Treasurer Scott Morrison says the Turnbull government is still working on its response to the Productivity Commission's review into how the GST is carved up among the states and territories.

Mr Morrison says the commission has identified a real problem and one the government is now trying to fix.

"We are taking our time to get it right and we will continue to take the necessary time to get it right," Mr Morrison told reporters in Canberra on Tuesday.

In May, Prime Minister Malcolm Turnbull promised the commission's final report would be released in June and before five by-elections on July 28.

Now, Mr Morrison says he will have more to say on the issue "over the balance of this week".

Any changes to how the GST is distributed could affect the coalition's chances in by-elections in Tasmania, South Australia and Queensland.

But the Liberals are not standing candidates in Western Australia, which is where the push to change the GST formula has been the strongest.

A change could result in Tasmania and South Australia losing some of their allocation, which is already above the amount of GST they raise.