What if rates drop after I sign my mortgage renewal?

This is the single most valuable piece of advice for anyone who has already accepted a renewal offer but hasn't yet started the new term: call your lender every time you see rates drop, and ask them to re-price your held rate. Most Canadian lenders will accommodate this once during the hold period; some will do it multiple times.

Once your new term is active, breaking to capture a lower rate rarely makes sense — IRD penalties on newly-closed fixed mortgages are typically 2%–4% of the balance, which usually exceeds the interest saved.