TORONTO — NDP Leader Andrea Horwath says Ottawa's plan to rush ahead with its HST legislation could mean people in Ontario will lose the few benefits attached the harmonized sales tax.

If the federal HST bill dies in the House of Commons, she says, people will lose the tax breaks promised by Premier Dalton McGuinty and funded through a $4.3-billion deal with the federal government.

That means the province would still be on the hook for a 13 per cent sales tax but won't have enough money to deliver personal and corporate tax cuts meant to soften the impact of harmonization.

The harmonized tax scheme is unpopular with consumers and is also opposed by the federal NDP, but the federal Liberals have been unclear about whether they support it.

Since the legislation to be introduced in Ottawa next week will be technical, there will not be a confidence measure that could force the government to fall and kill the bill.

But Horwath says this puts the process in motion and it means McGuinty shouldn't try to "ram" through provincial legislation enabling sales taxes to be merged.

British Columbia will also harmonize its provincial sales tax with the GST on July 1, something Quebec, New Brunswick, Nova Scotia and Newfoundland and Labrador have already done.