Petroleum marketers buy fuel on the basis of the "rack price" and the price set by refiners willing to supply Prince Edward Island retailers, mainly the Irving Oil Refinery in Saint John, New Brunswick, which, since August 2013 is the only oil refinery remaining in the Maritimes.
IRAC petroleum regulators then sets a "tank truck price" which includes Federal Excise Tax (10¢/L for gasoline and 6¢/L for diesel, as well as the provincial petroleum tax (13.1¢/L for gasoline and 20.2¢/L for diesel).
All prices have an additional 15% Harmonized Sales Tax (HST) added.
Consumers in Prince Edward Island are notified of any changes in the price via the IRAC website and through the media.
Price changes are closely guarded by IRAC to prevent runs on supply at local service stations.