The common language is that, on July 1st the GST and RST will be replaced by a single Harmonized Sales Tax. However, technically the Harmonized Sales Tax consists of two parts, the federal 5% portion and the provincial portion which is 8% in Ontario, Newfoundland, Nova Scotia and New Brunswick and 7% in BC. There are several situations where this distinction is important.

Point of Sale Rebate 
Some supplies that were previously exempt from RST will not be subject to the Ontario portion of HST (OHST) by offering a point of sale rebate.  Retailers of these exceptions need to ensure that their point of sale terminals and invoicing reflect the rebate which can be disclosed by either showing the full portion of the HST and a POS Rebate, or by netting the amounts.  The exception, where OHST is not applied (a Point of Sale Rebate) are on the following items:

• Children's clothing and footwear;
• Children's car seats and car booster seats;
• Diapers;
• Feminine hygiene products;
• Books and audio books;
• Printed newspapers;
• Accommodations (hotels etc.)
• Alcohol
• Admissions

Prepared food sold for $4 or less (ie. a breakfast sandwich and small coffee at Tim's is less than $4 so there is no OHST; a breakfast sandwich and extra large coffee is greater than $4 so OHST applies to the transaction) 

Other levies
There are currently rates of RST other than 8% on certain taxable supplies.  The Ontario government intends to charge an additional levy to make the total tax the same under the HST regime but has yet to determine the mechanism.  Be prepared for additional charges on:

PST marches on 
Retail sales tax will continue to apply to insurance premiums and private sales of used vehicles.