From a Calgary law firm:
Can You “lose” Vacation Days?
The law requires that employers give you your vacation within 12 months of you becoming entitled to it. This means that employers do not have to let you bank up holidays year over year and can instead adopt a “use-it-or-lose-it” policy.
However, even if an employee “loses” their vacation days because they have not been used by the end of the year, employers still must pay their employees for the vacation time.
https://getzcollins.com/can-my-emplo...ke-a-vacation/
A nice guide, but it does not answer the specific question.
https://www.alberta.ca/vacation-pay
Also, if employed over 5 years it is 6% not 4%. The guide talks how to calculate that.