Keep the Rate, Change the Address: How Mortgage Porting Works in 2026

For homeowners who locked into a fixed rate before rates climbed, moving home can feel like a trap: sell, buy, and risk exchanging a comfortable payment for a much higher one. Porting is the mechanism that can prevent that outcome. In plain English, it means asking your current lender to transfer the existing mortgage — and, crucially, its rate and terms — from the property you are leaving to the one you are buying. The mortgage is not automatically portable; the lender must agree, and the new property and borrower profile must fit its criteria. Used well, porting can be a sensible rate-preservation strategy. Used late, it can cause delays, extra costs or the loss of the very rate you were trying to keep.

What porting actually involves

Porting is not a case of lifting the mortgage paperwork from one address to another. The lender normally removes its charge from the old property and creates a new loan secured on the new one. The ported portion usually keeps the original product terms, including the fixed rate and any early repayment charge period, until the original product end date. If you need to borrow more, the additional amount is typically arranged as a separate loan or top-up on current rates. That means you may end up with two rates under one mortgage account: the old rate on the ported balance and a new rate on the extra borrowing. Ask the lender to show both figures in writing before you proceed.

Eligibility is not automatic

Lenders apply their usual affordability and lending criteria to the new property and to your circumstances. The new home must be acceptable security: the valuer will consider its type, condition, location and tenure. Leasehold properties may fail if the lease is short or the terms are restrictive. A flat above a commercial unit, a property with structural movement or a non-standard construction can also cause problems. Your income, credit file and debts will be reassessed. A change of job, a new credit card or a missed payment between the original application and the move can affect the outcome. Before you list your home, ask your lender whether porting is allowed and request a porting agreement in principle. Do not assume that because your current lender allowed porting for someone else, it will allow it for you.

Timing, chains and the porting deadline

Porting works best when the sale and purchase complete on the same day. Most lenders set a deadline for completing the new mortgage, often a few months from the sale of the old property. If the gap is longer, you may need bridging finance or a retention arrangement, both of which add cost and complexity. Tell your solicitor and broker early that you intend to port. Do not exchange contracts on your purchase until the lender has issued a formal mortgage offer for the new property. A porting agreement in principle is useful, but it is not a guarantee. If the purchase falls through after you have sold, the lender may treat the old mortgage as redeemed, which could trigger an early repayment charge. The sequencing needs to be managed carefully.

The cost side

Porting is not free. Lenders may charge an application or administration fee, a valuation fee and legal fees for the new security. If you borrow more, there may be a product fee on the top-up. If you borrow less than the outstanding balance, the difference is a partial repayment and may attract an early repayment charge, depending on your product terms. You will still pay conveyancing fees, stamp duty or the equivalent devolved tax, and removals. Compare the total cost of porting with the total cost of remortgaging. A lower rate is only valuable if the fees and charges do not swallow the saving.

When porting beats remortgaging

Porting usually makes sense when your existing rate is materially lower than current rates, you have a meaningful period left on the fix, and the early repayment charge on the old mortgage is high. It can also be the cleaner option if your circumstances have changed slightly and a new lender would apply stricter criteria. Remortgaging may be better if your current rate is no longer competitive, you need a much larger loan, you want to change term or repayment type, or you need a lender that accepts a property your current lender will not. Run the numbers over the remaining fixed period, not just the first month. Include fees, the cost of any top-up borrowing and the early repayment charge you would pay if you switched instead.

Common mistakes

The first mistake is assuming porting is guaranteed. The second is leaving it too late, after a buyer has been found or an offer has been accepted. The third is changing financial circumstances mid-process: moving jobs, taking on new credit or spending savings that were part of the affordability assessment. The fourth is ignoring the leasehold position on the new property. The fifth is forgetting that the top-up borrowing will be priced at current rates, not the old rate. The sixth is failing to get written confirmation of the ported amount, rate, term and fees. The seventh is treating the lender's valuation as a survey. It is not. If you are buying a home, commission your own survey.

Porting can be a valuable tool for homeowners who have a good rate and a good reason to move. It rewards preparation. Speak to your lender before you market your home, get the numbers in writing, and keep your finances steady until completion. If the arithmetic works, porting can let you change address without changing the rate that made your budget work. If it does not, remortgaging may be the more honest choice. General information only; not regulated financial advice.