Finance Minister Kevin Falcon says the transition from the harmonized sales tax back to the provincial tax and GST is proving to be more complex and difficult than expected.

British Columbians voted to scrap the HST in a province-wide referendum in August, and at the time the province said the transition would take 18 months.

Falcon said the federal and provincial governments are working as fast as they can to transition back to the old system, but said it's not clear when the transition rules will be in place.

Falcon was grilled on the issue in Question Period on Monday by NDP finance critic Bruce Ralston, who complained about delays in the switchover.

Ralston said realtors and home builders are complaining their businesses are in a sort of limbo waiting for more certainty about how and when the PST and GST will be reinstated.

But Falcon slammed Ralston and the opposition for campaigning against the tax and then nagging about how long it's taking to go back to the old tax regime.

"They should have thought about that, Mr. Speaker, when they were out campaigning to go back to a stupid, inefficient tax," Falcon said.

Ralston called Falcon's comments "arrogant and contemptuous of democracy."

With files from The Canadian Press