Porting a Mortgage in Canada: What Moves and What Does Not
Porting a mortgage is usually explained in a single sentence: you keep your rate when you move. That sentence is true, and it is the least useful part of the transaction. The rate is the piece every lender leads with. The pieces that decide whether a port is worth doing, or whether it is available to you at all, are a mortgage insurance premium with a published formula, two clocks that start on different dates, and a requalification on the new property that you can fail.
Canada Mortgage and Housing Corporation publishes the arithmetic for the first of those, in full, with its own worked examples. It is the part of a move that almost nobody reproduces, and for a household with less than 20% equity it is usually worth more than the rate.
What a port actually transfers
The Financial Consumer Agency of Canada is precise about it. “If you sell your home to buy another one, a portable mortgage allows you to transfer your existing mortgage. This includes the transfer of your mortgage balance, interest rate and terms and conditions,” the agency says on its page on choosing a mortgage. Elsewhere it puts the point more bluntly: porting “saves you from breaking your mortgage contract and getting a new one.”
Two cautions sit in the same FCAC section and both matter. The first is that portability is a contract feature rather than a right, so it has to be checked: “Check with your lender to see if your mortgage is eligible for porting. Ask about any restrictions that may apply.” The second is the one that surprises people moving down rather than up. “If your new home costs less than the amount of your mortgage, you may pay a prepayment penalty.” Shrinking a mortgage is a prepayment, and it is priced like one. If that is your situation, the size of the bill is set by the interest rate differential or the three-months-interest rule, which we worked through in breaking a mortgage in Canada.
What the rate is worth, in dollars
The value of a port is not the rate you keep. It is the gap between the rate you end up paying on the whole new loan and the rate you would have signed today, multiplied by the months left in your term.
Take a household with $450,000 left on a mortgage at 3.19%, 22 years of amortization remaining and 36 months left in the term, moving to a $700,000 home with a $600,000 mortgage. That is $150,000 of new money. These are illustrative assumptions, not data and not a forecast.
New money does not come at the old rate. Lenders blend, and the blend that applies here weights the two rates by dollars: the ported balance at 3.19% and the new $150,000 at whatever the lender is quoting. Payments below are computed with interest compounded semi-annually, as Canadian mortgages are under section 6 of the Interest Act, which requires the rate to be stated “calculated yearly or half-yearly, not in advance.” The arithmetic is ours.
| Rate on the new money | Blended rate | Payment, blended | Payment at market | Monthly difference | Over the 36 months left |
|---|---|---|---|---|---|
| 4.00% | 3.3925% | $3,221.05 | $3,410.48 | $189.43 | $6,819.40 |
| 4.50% | 3.5175% | $3,259.57 | $3,570.57 | $311.00 | $11,196.12 |
| 5.00% | 3.6425% | $3,298.32 | $3,734.32 | $436.00 | $15,696.03 |
| 5.50% | 3.7675% | $3,337.32 | $3,901.63 | $564.31 | $20,315.20 |
Note the shape of it. Porting a rate that is only 81 basis points better than today’s market is worth $6,819.40 over the rest of the term. Porting one that is 231 basis points better is worth three times that. The further rates have moved since you signed, the more a port is worth, which is also precisely when lenders are least eager to process one.
The insurance premium is where the larger money usually sits
Where the down payment is less than 20% of the price, FCAC says you will usually need mortgage loan insurance, and the premium is charged once, at the start, though CMHC says it “may be added to the insured loan amount.” Porting changes how that premium is calculated, and the change is large.
CMHC’s Portability feature sets out three cases.
Straight portability. The amortization on the new loan does not exceed what was left on the old one, the new loan-to-value is equal to or lower than the current one, and the new loan is no larger than the outstanding balance. CMHC’s own example: a $550,000 balance, which is 91% of the original $600,000 purchase price, moving to a $450,000 loan at 90% on a cheaper $500,000 property. No new money, no increase in loan-to-value, no increase in amortization. “There is no premium to be charged.”
Portability with an increase in loan-to-value. Here the premium is charged only on the increase in the ratio. CMHC works it in three steps: a jump from 90% to 94% is a 4% increase, 4% of the new $475,000 purchase price is $19,000, and $19,000 multiplied by the 6.30% top-up factor for that band is $1,197.00.
Portability with an increase in the loan amount. This is the common case for anyone moving up, and it carries the rule worth knowing. The premium is the lesser of two calculations: the top-up rate applied to the new money, or the ordinary rate applied to the entire loan. In CMHC’s example, $115,000 of new money at 6.25% is $7,187.50, while the whole $450,000 loan at 3.10% is $13,950.00, and the borrower is charged the first.
The rates come from CMHC’s published schedule for owner-occupied homes of one to four units.
| Loan-to-value | Premium on the total loan | Premium on the increase, porting |
|---|---|---|
| Up to and including 65% | 0.60% | 0.60% |
| 65.01% to 75% | 1.70% | 5.90% |
| 75.01% to 80% | 2.40% | 6.05% |
| 80.01% to 85% | 2.80% | 6.20% |
| 85.01% to 90% | 3.10% | 6.25% |
| 90.01% to 95% | 4.00% | 6.30% |
| 90.01% to 95%, non-traditional down payment | 4.50% | 6.60% |
Run the household above through it. A $600,000 mortgage on a $700,000 home is 85.71% loan-to-value, which lands in the 85.01% to 90% band. The premium on the increase is $150,000 at 6.25%, or $9,375.00. The premium on the whole loan is $600,000 at 3.10%, or $18,600.00. CMHC charges the lesser, so the bill is $9,375.00 and the port has saved $9,225.00.
That is the number to hold onto. At a market rate of 4.00%, the rate advantage over the remaining term was worth $6,819.40. The insurance premium saved was worth more, and it is paid at closing rather than spread over three years.
One surcharge to watch. If the amortization is blended rather than held at what was left, CMHC applies a 0.60% surcharge to the increase in the loan amount.
Two clocks, starting on different dates
CMHC attaches timing conditions to the feature, and it words the two of them differently.
The request window is tied to the sale. Under its portability requirements, CMHC states that the original property “must be sold, and the new loan should finance the purchase of the new property,” and that “the insurance request using the portability feature must be received within 6 months of the original property’s closing date.”
The premium credit runs on a different clock, measured in the table’s own words from the “original closing date of existing CMHC-insured loan to the new request for loan insurance.” Port within 6 months of that date and 100% of the premium already paid is credited. Within 12 months it is 50%. Within 24 months it is 25%. After two years the insurance is still portable, but no credit applies.
CMHC’s example of the credit: a full premium of $13,950.00 on the new loan, against a premium of $11,857.50 paid eight months earlier, gives a 50% credit of $5,928.75 and a premium due of $8,021.25.
Because the two windows are anchored to different events, ask your lender which date CMHC will measure you from before you assume either one. Three further conditions are easy to trip over: the loan on the original property must be in good standing and not in arrears, the new property must have the same intended use as the old one, owner-occupied or rental, and at least one borrower on the new loan must have been on the original insured mortgage.
What does not come with you
The land transfer tax. It is charged on the transfer of the property, not on the mortgage, so carrying the loan across changes nothing about it. Moving means paying it again on the new home, at the province’s rates, with a second municipal tax on top in Toronto. The schedules are in land transfer tax in Canada.
The approval. A port is new underwriting on a new property. OSFI’s minimum qualifying rate for uninsured mortgages is the greater of the contract rate plus 2% or 5.25%, and OSFI states that Guideline B-20 sets its expectation that lenders apply that rate “to most newly underwritten residential mortgagors.” The single carve-out OSFI publishes is narrow: it does not expect the test on uninsured straight switches at renewal, where a borrower moves to another federally regulated lender with no increase to the amortization period or the loan amount. Buying a different house is not that. If your income or debts have changed since you last qualified, the stress test and the debt-service ratios are where a port fails, and both are worked through in how much mortgage you can afford.
Assumption: the other way a rate survives a sale
There is a second route, and it points the opposite direction. Rather than carrying your rate to a new house, you hand it to the buyer of your old one.
“An assumable mortgage allows you to take over or assume someone else’s mortgage and their property,” FCAC says. “The terms of the original mortgage must stay the same.” FCAC puts the option on most fixed-rate mortgages and states it is “not available with variable-rate mortgages and home equity lines of credit.” The lender must approve the buyer, who then takes over the payments and is responsible for the terms and conditions in the contract. Lenders may charge a fee for it.
FCAC is clear about who this suits: a buyer when interest rates have risen since the seller signed, and a seller who wants to move somewhere cheaper without paying a prepayment penalty on several years of remaining term. It is also clear about the risk a seller carries. “In some provinces, the seller may remain personally liable for the assumable mortgage after the sale of the property. If the buyer doesn’t make their mortgage payments, the lender may ask the seller to make the payments.” Some lenders will release the seller when they approve the buyer. That release is the thing to negotiate, and it is not automatic.
For a buyer, there is one cost that shows up years later. CMHC states flatly that “the Portability feature is not available where an insured mortgage was assumed.” Assume an insured mortgage to capture a below-market rate today, and the insurance on it cannot be ported when you move next time. The rate you inherited came with the portability stripped out.
The questions worth asking before the sign goes up
Whether the mortgage is portable at all, and under what restrictions. Whether the lender blends by dollars or by dollars and time, because the two produce different rates. Whether the new loan-to-value or the amortization will move, since either one changes the premium calculation. Which closing date CMHC will measure the six-month window and the premium credit from. And if you are selling with a buyer who wants to assume, whether the lender will release you from the covenant in writing.
The rate is the headline. It is rarely the biggest number on the page.
Disclaimer: The content on bestcanadianstocks.ca is for informational and entertainment purposes only and does not constitute financial advice. Past performance is not indicative of future results. Always consult a qualified financial advisor before making investment decisions. CMHC Portability product page (premium schedule, the three portability cases, the premium credit table and the assumed-mortgage exclusion), fetched live September 21, 2026. OSFI minimum qualifying rate page for uninsured mortgages, date modified January 29, 2026. Interest Act section 6 from Justice Laws. FCAC portable and assumable mortgage sections from canada.ca. Blended-rate and premium arithmetic is ours, validated against CMHC’s four published worked examples and FCAC’s own payment example.
