Less than 24 Hours - $0 CAD
There is no duty free allowance for absences of less than than 24 hours.

24 Hour Exemption $200 CAD
If you are absent from Canada for more than 24 hours, you may claim up to $200 CAD worth of goods duty free as your personal exemption and all goods must be with you when you arrive. If the goods you bring in are worth more than $200 CAD in total, you cannot claim this exemption and you will have to pay duties and taxes on all goods you bring in to Canada. You can NOT include tobacco or alcoholic under this exemption.

48 Hour Exemption $800 CAD
If you are absent from Canada for more than 48 hours, you may claim up to $800 CAD worth of goods duty free, and must have the goods with you when you arrive at the border. You may include some tobacco and alcohol products under this exemption, and should review the section below called "Alcohol and Tobacco" for more details.

7 Day Exemption $800 CAD
If you are absent from Canada for more than 7 days, you may claim up to $800 CAD worth of goods duty free. You may include some tobacco and alcohol products under this exemption, and should review the section below called "Alcohol and Tobacco" for more details. With the exception of tobacco and alcohol products, you do not need to have the goods with you when you arrive at the border. To calculate the number of days you have been absent, do not include the date you left Canada but include the date you returned. Dates matter, not times. For example, you are considered to have been absent for seven days if you left Friday the 7th and returned Friday the 14th.

What are Duties?
The term "duties" includes excise taxes and GST/HST. It does not include provincial or territorial sales tax. However, the CBSA has working agreements with some provinces and territories that allows them to collect provincial and territorial taxes, levies and fees on goods that have a value higher than your personal exemption.