Canada has no equivalent of the American short sale process, so nothing about this is standardised. You speak to your lender's mortgage servicing or special accounts group, tell them plainly where you are, and ask what they will accept. Lenders generally prefer a negotiated sale to enforcement, which in Saskatchewan runs through the Court of King's Bench and is slow and expensive for them.
Build the real number before you list. Add the mortgage payout, any prepayment penalty, seller closing costs of 4 to 6 percent including commission, and legal fees of $800 to $1,500. The penalty is the line people forget, and on a fixed rate it can be an interest rate differential calculation rather than three months of interest.
There is also a decent chance you are not actually underwater. The Saskatchewan REALTORS Association benchmark is $444,700, up 2.8 percent year over year, and improvements you have made without a permit never reached any record or online estimate. Joel Dyck's hand-reviewed valuation establishes the real figure before you accept that you are short.