More than a day after B.C.'s new harmonized sales tax took effect, confusion at the till means that consumers may be paying more -- or less -- than they should.

Since the HST kicked in on Thursday at midnight, cash register technician Doug Boudreau's phone hasn't stopped ringing with requests to change reprogram tills.

"Last night, I stopped at about 10 o'clock and the phone rang, and I programmed over the phone until 11," he said. "We're about three-quarters of the way there, and we'll still be changing them by July the 5th, 6th and 7th."

Boudreau told CTV News that the retailers he deals with are just as confused as consumers about what they should be charging the new tax on.

"That's a big problem in our business, because they all think I'm supposed to tell them what's taxable and non-taxable."

Barb Rezansoff, a cafeteria manager at BCIT, said she hasn't received any information about which products are taxable.

"No one has defined anything. We have received nothing," she said.

While she waits to hear otherwise, Rezansoff said that she's decided to charge HST on all of her products.

"Just the 12 per cent on everything…until we get further notice."

Some businesses have taken the opposite approach. When CTV News bought a taxable first aid kit at Shoppers Drug Mart on Thursday, the store only charged five per cent, not the full 12.

But if retailers don't get up to speed quickly, the government could force them to pay missing HST charges out of their own cash registers.

Watch CTV News at Six for a report from Shannon Paterson