More than 1,200 items are now subject to a new surtax at the Canada border.
The Department of Finance says the 25% is applied when the items are brought into Canada from the United States for personal or commercial purposes.
It includes hundreds of grocery items such as meat, dairy products and certain fruits and vegetables.
Lumber products, clothing and appliances purchased in America are also subject to the additional tax.
The surtax is in addition to other duties and taxes that may be applicable.
Collection began midnight Tuesday.
The complete list of affected products can be found by clicking here.