About Harmonized Sales Tax (HST)
Three provinces - Nova Scotia, New Brunswick, and Newfoundland and Labrador - harmonized their provincial sales tax with GST to create HST. These three provinces are known as participating provinces. Effective January 1, 2008, the GST rate is reduced from 6% to 5%, and the HST rate from 14% to 13%.
The HST is composed of the GST and the 8% provincial tax and applies to the same base of goods and services that are taxable under GST. HST follows the same general rules as GST.
GST/HST registrants continue to collect GST on taxable supplies (other than zero-rated supplies) of goods and services made in Canada outside the participating provinces. On supplies made in the participating provinces, they collect HST. All GST registrants are automatically registered for HST.
Source: http://www.cra-arc.gc.ca/tx/bsnss/tpcs/gst-tps/gnrl/hst-tvh/wrks-eng.html