From Triathlon Canada:

Expression of Interest

An expression of interest is the mechanism by which athletes confirm their intention to compete and accept a place at the Age Group World Championships if they qualify. By expressing intent, the results can be filtered to a final list of athletes who wish to compete at the World Championships, and places can be “rolled-down”.  The application will open 3 weeks before each race and close the day before the event.

All athletes seeking to compete for a place must submit an Expression of Interest prior to each qualifying event. An online page will be available for each event and discipline.

There will be a $20 fee to complete the Expression of Interest to encourage only serious athletes to apply for a spot. The $20 will be considered a deposit for those who are successful in obtaining a spot and will be deducted from their race entry fee. The $20 fee will not be refunded for athletes who are not successful in obtaining a spot. However, it can be applied to a charity entry.