In early August, when he was treasurer, Morrison admitted the tax should never have applied to sanitary items and promised to "remediate" the situation.

"I think it's an anomaly that has been built into the system for a long time and the states have decided to hold onto the money instead of getting rid of it," he said.

Labor proposed a plan in April to scrap the tax and offset any losses in revenue by applying the tax to 12 natural remedies currently exempt from GST.