The federal minister called an interim report that recommended cutting WA's share of the GST as "clearly incorrect" and said the resource-rich state had the prime minister's backing.

The Productivity Commission finds the WA GST deal is a "costly mistake" that has led to "perverse" outcomes, and recommends it be scrapped.

The federal minister called an interim report that recommended cutting WA's share of the GST as "clearly incorrect" and said the resource-rich state had the prime minister's…