Two sides in the battle over B.C.'s harmonized sales tax are taking their fight to Canada's advertising watchdog, each claiming the other is misleading voters ahead of the HST referendum.

The pro-HST Smart Tax Alliance filed a complaint with Advertising Standards Canada on Saturday, claiming that the Fight HST group "has decided to mislead the public."

The television spot in question features former premier and anti-HST campaigner Bill Vander Zalm saying "Vote yes to extinguish the HST, and keep all your money."

Smart Tax Alliance co-chairman Mike Jagger says that claim could lead people to believe they'll be refunded or allowed to keep the HST they've paid.

"They are wrong and we won't allow them to go unchallenged. We feel the ad is clearly inaccurate," Jagger said in a statement.

The Fight HST movement is calling the move "desperate."

Meanwhile, outspoken BC Conservative Dean Skoreyko says he's filed his own complaint with the standards body, claiming that the Smart Tax Alliance is the one guilty of false advertising.

In his complaint, Skoreyko writes that a television ad from the group makes the "patently false" statement that the HST has already been reduced to 10 per cent.

"The decrease in the HST from 10 per cent to 12 per cent saves us all money," orchard owner Christine Dendy says in the ad.

Premier Christy Clark has promised to cut the unpopular tax if voters choose to stick with it, but the change won't come into effect until 2014.

The HST referendum ballots began going into the mail on June 13 and Elections BC says that the deadline to return them is still July 22, despite the ongoing Canada Post lockout.