If you are moving house partway through your term, porting is the word you will keep hearing, so here is what it means. Porting moves your existing mortgage, rate and terms included, from the home you are selling to the one you are buying, which can save you the penalty for breaking mid-term. Most fixed mortgages are portable on paper. In practice there are tight timelines and a requalification involved, and now and then paying the penalty is genuinely the better deal. Here is how to tell which one you are looking at.
What a port actually is
Your mortgage is a contract with a rate and an end date on it. When you sell partway through, the default outcome is breaking that contract, and a fixed-rate penalty worked out on the interest rate differential can run into five figures. A port transplants the contract instead: the same lender, the same rate, the same maturity date, a new house. If you are holding a lovely rate from a few years ago, that is real money kept in your pocket.
If you need more money, that is a blend
Most people move up rather than sideways, so the new home needs a bigger mortgage. Lenders handle that with a blend: your existing balance keeps its old rate, the new money comes at today's rate, and the two are blended into one payment. It is tidy, and it is also exactly where you want a second pair of eyes, because a blended rate can quietly cost more than breaking and taking a fresh mortgage somewhere sharper. I run both versions side by side before I suggest either one.
A port is a tool rather than a default. The only way to know it is the right tool is to price the alternative beside it.
The two things that catch people out
There are two surprises in here. The first is the window. Most lenders give you somewhere between 30 and 120 days between selling and completing on the new purchase to carry out a port. Sell in March, buy in September, and the port may simply be off the table. The second is that you requalify. The lender underwrites your income, your credit and the new property again from scratch. A port is not a right you hold, it is a fresh application with your old pricing attached to it.
When breaking beats porting
If today's rates sit below your contract rate, the penalty may be well worth paying to reset at a better one, particularly early in a term. If your lender's blend offer comes back weak, then the whole rest of the market is your alternative, and that is a comparison your branch will not offer to run for you. And if your timeline cannot fit inside the port window, the decision rather makes itself. This is renewal-adjacent territory, so the renewal playbook pairs nicely with it, and broker against bank explains who actually runs these numbers for you.
Questions people ask me
Can I port a variable-rate mortgage?
Usually not directly. A variable mortgage normally has to be broken, though the penalty on one is typically three months of interest, which is far smaller than a fixed-rate differential penalty. Some lenders will let you convert to fixed first and then port.
How long do I have to port my mortgage?
It varies from lender to lender, commonly somewhere between 30 and 120 days between your sale closing and the new purchase completing. The exact window is written into your mortgage contract, and it is well worth knowing before you list.
Do I have to requalify to port?
Yes. The lender looks at your income, your credit and the new property again from scratch. A port preserves your rate rather than your original approval.
