Mortgages
Porting a Mortgage: What Is It and How Does It Work?
Porting a mortgage means transferring your existing mortgage deal — the same rate and terms — to a new property when you move, instead of paying it off and starting again. It is useful if you are tied into a fixed rate with early repayment charges, because it lets you keep the deal and avoid the penalty. But porting is not guaranteed: you must re-apply and pass the lender’s current affordability and valuation checks, and extra borrowing is usually on a separate, current-rate product.
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- Same ratecarried to a new home
- Avoids ERCpotentially thousands
- Re-applyit is not automatic
- Chain risksale & purchase must align
How porting works
When you sell and buy at the same time, a portable mortgage lets you carry your existing interest rate and conditions across to the new home. Technically the old loan is repaid on your sale and a new loan on the same terms is granted on your purchase, so the two must complete simultaneously. The big attraction is avoiding early repayment charges (ERCs) on a fixed deal, which can run to thousands of pounds, while keeping a rate that may be better than anything available now. Most modern mortgages are portable, but you should confirm yours is.
When porting helps — and when it does not
| Porting tends to help when… | Porting is less useful when… |
|---|---|
| You are mid-fix with hefty ERCs | Your current rate is poor |
| Your existing rate beats today’s deals | You are downsizing and borrowing much less |
| Your circumstances are stable | Your income or situation has worsened |
| The new property meets lender criteria | The new property is a non-standard type |
Because lenders reassess you afresh, a drop in income, a new dependant, or a lower property valuation can see a port declined even though you already hold the mortgage.
The catches to check
Before relying on porting, confirm:
- Your mortgage is actually portable (most are, but not all).
- The lender will lend on the new property type and value.
- How any additional borrowing is priced — top-up borrowing usually sits on a separate product at current rates, leaving you with two sub-accounts on different end dates.
- Whether borrowing less triggers a partial ERC on the reduced amount.
- That your sale and purchase can complete together — a broken chain can scupper a port.
Porting vs remortgaging
Porting is not always the cheapest option. Sometimes paying the ERC and remortgaging onto a new deal works out better overall — especially if current rates are lower than your existing one, or if the extra borrowing on a split product would be expensive. The only way to know is to compare the total cost of each route: the ERC saved by porting versus the rate and fees of a fresh remortgage. A mortgage broker can run both calculations quickly and advise which leaves you better off.
Porting when you are also selling fast
Porting depends on your sale and purchase completing together, so the certainty of your sale matters. If your onward chain is fragile, a delay or collapse can break the port and leave you facing the ERC anyway. Where a guaranteed, chain-free completion is important — for example to protect a fixed-rate deal you want to keep — a cash sale of your current home gives you a reliable date to align with your purchase. Read selling with an outstanding mortgage for how the redemption fits in.
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Written & reviewed by Lisa Hayes, Founder
Lisa Hayes is the founder of Ready Steady Sell and an independent UK home-selling expert with over a decade helping homeowners weigh cash house buyers, property investors and the wider fast house-sale industry — without pressure or hidden fees. Every guide is reviewed for accuracy under our editorial standards.
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Frequently asked questions
Straight answers, no sales talk
Is porting a mortgage guaranteed?
No. Even though you already have the mortgage, the lender reassesses your affordability and values the new property, so a port can be declined if your circumstances have changed.
Does porting avoid early repayment charges?
Usually yes, if you port within your deal period and complete the sale and purchase together. Borrowing less can still trigger partial ERCs on the reduced amount.
Can I borrow more when porting?
Often yes, but the additional borrowing is typically a separate product at current rates, so you end up with two parts to your mortgage on different terms and end dates.
Is it better to port or remortgage?
It depends on the numbers — compare the ERC saved by porting against the rate and fees of a fresh remortgage. A broker can calculate both and advise which is cheaper overall.
What happens to porting if my chain breaks?
Porting needs your sale and purchase to complete together, so a broken chain can prevent the port and may leave you liable for the early repayment charge. A chain-free sale reduces this risk.
Are all mortgages portable?
Most modern mortgages are portable, but not all, and portability does not guarantee approval. Check your mortgage terms and confirm with your lender before relying on it.