Rare at filing
Common when requesting examination
Canada does not have special rules about the number or structure of permissible claims: claims that are acceptable under US practice or EPO practice will usually conform with Canadian rules.
Similarly, Canada does not charge extra government fees when you file a patent application with multiple claims or multiple claim dependencies (that is, there are no extra fees for the total number of claims, the number of independent claims, or ‘multiple dependent claims’, as there are in some jurisdictions).
Accordingly, it is rare to make voluntary amendments coincident with filing into Canada (either Convention or PCT). Voluntary amendments in Canada are usually made later, just prior to requesting examination and ideally after successful prosecution in another jurisdiction (eg. US) which can then be used to invoke rapid treatment in Canada under the ‘patent prosecution highway’ (recall that examination in Canada is deferred without charge until the applicant requests it for up to 5 years from the International Filing Date).