Deputy opposition leader Tanya Plibersek has demanded the prime minister makes scrapping the GST on sanitary items a "priority" after he promised to weeks ago.
"The tampon tax is unfair and discriminatory," Plibersek wrote in a letter sent late Thursday afternoon to Scott Morrison.
"Scrapping it will make sanitary products more affordable for women and will end an unnecessary inequity in our taxation system."
Plibersek urged Morrison to ensure the matter would be placed on the agenda for the meeting of the Council on Federal Financial Relations next week.
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.