The following is available in its entirety on the Canada Border Services Agency website.
D10-0-1 – Classification of Parts and Accessories in the Customs Tariff
This memorandum has been updated to clarify the Canada Border Services Agency’s administrative policy regarding the classification of parts and accessories in the Customs Tariff (Tariff).
This memorandum will serve to assist users of the Tariff to determine the proper tariff classification of parts and accessories
For an article to be classified as a part of a good it must be committed for use with those goods.
An article that can be used with goods other than those described in a heading, subheading or tariff item is not to be regarded as so committed. An article which has no other use than with such goods and is necessary to their function is committed for use with them.
Five criteria have emerged over the years which set forth basic considerations for the classification of parts. To be considered to be a part, goods:
(a) form a complete unit with the good
(b) have no alternative function
(c) are marketed and shipped as a unit
(d) are necessary for the safe and prudent use of the unit and/or
(e) are committed to the use of the unit
These considerations have no particular order of precedence. Used individually or in combination, they are useful in determining whether or not an article constitutes a part.
For an article to be considered an accessory it must be solely or principally for use with a particular good and must supplement the functionality of that good.