45(3) Election

Is the 45(3) election submitted in the year of change or when the property is sold, which may be years later?

When the property is sold/disposed.

Thanks for the feedback.

What is confusing about when the election is to be submitted is that it is not submitted until you sell the property and yet the main purpose of the election is to defer any capital gain income inclusion at the time of change in use. Makes me question - the rationale for having to submit this election, other than to add four more years to the principal residence calculation.