Blend-and-extend or break-and-switch: the penalty is the deciding factor, not the rate.

Some lenders allow a client to renew early, before the end of their term, by blending their old contract rate with the lender's current rate and extending the length of the mortgage. Because the old rate and the new one are averaged together rather than the contract being broken, no prepayment penalty applies. It's a lender-offered early renewal option, not a right written into every mortgage contract.

The blend is typically weighted by how much time is left on the original term versus the new term being added, so a client with only a few months left on their current rate ends up with a blended rate much closer to today's market than someone who still has years remaining.

Breaking a mortgage contract before the end of the term — whether to switch lenders, refinance, or sell — triggers a prepayment penalty. Lenders calculate that penalty as the greater of three months' interest on the outstanding balance or the interest rate differential (IRD), which estimates the interest the lender loses by re-lending the money at today's rate.

On a $200,000 balance with 36 months left in a 5-year term, three months' interest might run around $3,000 while the IRD could run to $12,000 or more, depending on how far the client's rate sits above the lender's current posted rate for a comparable term — the client pays whichever figure is higher.

The IRD calculation usually applies whenever the client's current rate is higher than the lender's current posted rate for a similarly-termed mortgage and the contract was signed less than five years ago. Big banks often calculate the IRD using their posted rates rather than the discounted rate the client actually pays, which tends to produce a larger penalty than a credit union or monoline lender comparing contract rates directly.

It fits best when the blended rate lands close to what's actually available in the market and the client values staying with a lender they already know, avoiding new paperwork and a new registration. It's worth remembering the lender isn't obligated to offer it — a client needs to ask, and the blended rate offered is set at the lender's discretion.

It also tends to suit a client who simply wants certainty and speed over squeezing out the absolute lowest rate available — there's no new underwriting, no new appraisal, and no risk of a declined application with a lender the client hasn't worked with before.

It's worth paying the penalty when the interest saved on a genuinely better rate over the new term outweighs the penalty cost — not simply because a competing rate looks lower on paper. A rate that looks a full percentage point better can still be a poor trade once a five-figure penalty is factored in, especially if the client expects to move again within a couple of years.

1. 01Get an exact penalty quote from the current lender, not an estimate — penalty calculations vary between lenders.
2. 02Compare the lender's blended rate offer against the best rate genuinely available elsewhere in the market.
3. 03Calculate the breakeven point: how long it takes the interest savings on a new rate to cover the penalty paid to get there.

This kind of rate-movement volume tends to spike around renewal season — see where the 2026 renewal wave is concentrated for the scale of files this affects, and lean on Treadstone's fulfillment associates to run penalty comparisons across a full pipeline instead of one file at a time.

Documenting the comparison in writing for the client — even a simple one-page summary of both numbers — also protects the broker later if rates move again shortly after the decision is made. A client who can see exactly why a choice made sense at the time it was made is far less likely to second-guess it six months on.