Killing the controversial harmonized sales tax in British Columbia will be a boost for Ontario, Premier Dalton McGuinty said Tuesday.

Ontario, which also merged the federal GST with the provincial sales tax July 1, will benefit if B.C. ends up dumping the unpopular tax, he said.

“There’s no doubt about it — it will give us a competitive advantage,” McGuinty said.

Asked whether he wanted B.C. residents to vote down the tax next fall, McGuinty laughed, saying it’s also in Ontario’s interest that all provinces do well economically.

McGuinty has often defended the HST, saying it will save businesses billions of dollars by reducing layers of taxation.

His comments come after B.C. Premier Gordon Campbell promised to let voters decide whether that province should scrap the unpopular tax.

Campbell said he’ll forego official rules and turn next September’s referendum into an election-style simple majority vote on the future of the tax.

His Liberal government was forced into either holding a non-binding referendum or putting the issue to a vote in the legislature after anti-HST forces gathered more than 500,000 signatures on a petition.

B.C. voters will head to the polls at the same time Ontario will be in the throes of an election campaign.

McGuinty said the October 2011 election will effectively be an Ontario referendum on the HST.

“Elections are always referendums on all the actions taken by a government,” he said in French.

Many Ontario residents have voiced their dissatisfaction with the tax, but there’s been no movement like the one in B.C. to get rid of it.

The federal government is providing $4.3 billion to Ontario and $1.6 billion to B.C. to make the change, which B.C. would have to pay back if it reneges on its agreement with Ottawa.