What is Good cause?

Claimants who request an antedate must show good cause for not filing at the earlier date. Jurisprudence has held that good cause is simply doing what a reasonable person would do to satisfy themselves as to their rights and obligations under the Act. Therefore, an individual who makes the assumption that he or she does not qualify, is indifferent or lacks concern as to his or her circumstances, or makes no effort to ascertain his or her rights and obligations cannot be said to have good cause because they cannot be said to have acted as a reasonable person would.

Good cause, subject to the section below, must be shown to have existed throughout the whole period of the delay. It is not necessary to account for every single day but it must be readily concluded that there was good cause without any break for the whole period. Furthermore the reason for the delay need not be the same throughout the period. There may be a succession of reasons provided each is considered to be good cause.

There can be no part-way positions based on for example mitigating circumstances saying that the claimant had some justification for the delay even if good cause was not present. There can only be one decision–either there was good cause or there was not.

https://www.canada.ca/en/employment-social-development/programs/ei/ei-list/reports/digest/chapter-3/conditions.html

(Source: Service Canada website)