You have found the right new home, but your current mortgage deal still has two years left to run. Ending it could trigger a sizeable early repayment charge. This mortgage porting guide UK explains the alternative: taking your existing mortgage product with you when you move, while making sure the figures genuinely work for your next step.
Porting can be useful, particularly when your current fixed rate is lower than the rates now available. It is not, however, a simple case of transferring a loan from one address to another. Your lender will reassess your circumstances and the property you want to buy. The result can be a valuable way to avoid charges, or a process that is less suitable than arranging a new mortgage.
What does porting a mortgage mean?
Mortgage porting means moving your existing mortgage deal from your current home to a new one. The interest rate, remaining fixed or tracker period, and key terms of that deal may continue on the amount you port. This is why it appeals to homeowners who would otherwise need to repay their loan early and pay an early repayment charge, often called an ERC.
The mortgage itself is not physically moved. Your old mortgage is repaid when your sale completes and a new mortgage is arranged on the new property, usually at the same time. The lender agrees to apply your existing product terms to the replacement borrowing, subject to its checks and conditions.
Portability is a feature of many, but not all, mortgage products. Even where it is available, it is not guaranteed. Your lender will normally carry out a fresh affordability assessment, review your credit profile and value the property you are buying.
How mortgage porting works when you move home
The process usually starts before you put in an offer, or as soon as your move becomes likely. Ask your lender whether your product is portable, how much you can transfer and whether any deadlines apply. Your adviser can then compare the porting route with the wider mortgage market, rather than assuming the existing deal is automatically the best answer.
If you are borrowing the same amount or less, the arrangement may be relatively straightforward, provided you still meet the lender’s criteria. If you need to borrow more, the extra borrowing is usually placed on a separate product at the lender’s current rate. This is often called a top-up or additional borrowing tranche.
That can leave you with two mortgage parts, each with its own rate and end date. For example, you may port £180,000 at your existing fixed rate and borrow another £70,000 at a newer, higher rate. The blended monthly payment may still be attractive, but the two-part structure needs careful planning when one deal ends before the other.
The lender will also assess the home itself. A property type, condition or construction method that falls outside its lending policy could prevent the port, even if your finances remain strong. If the valuation comes in lower than expected, your deposit position and the loan-to-value ratio may change too.
When porting may save you money
Porting is most compelling when your existing rate is substantially below current rates and an ERC would be expensive. It can also help where you have a competitive product with time left to run and only need a modest amount of additional borrowing.
Say you are selling with a £200,000 mortgage and your fixed deal has 18 months remaining. A 3% ERC would cost £6,000 if you simply redeemed the loan. If the product is portable and the new lending meets the lender’s rules, porting could preserve your rate and avoid that cost.
But the ERC should not be viewed in isolation. A new mortgage with another lender could sometimes offer lower payments or better flexibility, even after the charge is included. Your choice should be based on the total cost over the period you expect to keep the mortgage, alongside product fees, legal costs, valuation fees and the practical needs of your move.
The trade-offs to check before you port
You must qualify again
A mortgage offer from several years ago is not a promise of future lending. Changes to income, employment, childcare costs, committed credit, credit history or retirement plans can affect affordability. Lenders also apply their current criteria, which may be different from the rules in place when you first borrowed.
This matters for homeowners moving after a job change, taking parental leave, becoming self-employed or increasing other commitments. A conversation early in the process gives you time to understand what is realistic before you become committed to a purchase.
The extra borrowing may not be competitive
The ported balance can retain an excellent rate while the additional borrowing is priced at the lender’s current range. If you need a significant top-up, compare the overall cost carefully. A low rate on one part of the loan does not necessarily make the combined arrangement the cheapest option.
Your mortgage end dates can become awkward
Two product end dates can make future remortgaging more complicated. Leaving one part early may trigger an ERC, while waiting for both parts to end could mean spending time on a lender’s variable rate. This is manageable, but it should be planned rather than discovered later.
Timing can affect the ERC
Some lenders require your sale and purchase to complete on the same day to avoid an ERC. Others allow a limited gap, sometimes known as a porting window, provided the new mortgage completes within a specified period. If you are selling first and renting temporarily, or your chain is uncertain, confirm the rules in writing before relying on them.
Documents and details to prepare
Mortgage porting still involves an application, so preparation can help the process move more smoothly. You will normally need recent proof of income, bank statements, identification, details of existing credit commitments and information about the property you are buying. Self-employed applicants may also need accounts, tax calculations or other evidence of income.
Keep an eye on your credit report and avoid taking out unnecessary new borrowing while the application is under review. A car finance application, new credit card or missed payment can change the picture at the wrong time. It is also sensible to keep your deposit funds traceable, as the lender and conveyancer may need to see where they came from.
With adviser-led support, documents can be provided electronically and queries dealt with as they arise. That does not remove lender checks, but it can remove much of the chasing and uncertainty that makes a home move feel harder than it needs to be.
Questions to ask your lender or adviser
Before you decide, get clear answers on whether your current product is portable, the ERC if you do not port, the maximum amount you can transfer and the rate available for any extra borrowing. Ask whether the lender permits a gap between sale and purchase, which fees apply, and what happens if your purchase falls through after your sale completes.
It is equally useful to ask for a comparison against alternatives. The right option may be to port all of your mortgage, port part of it and arrange additional borrowing, or take a completely new deal. Your property plans, borrowing needs, credit position and the time left on your current rate all matter.
Mortgage porting guide UK: the right next move
Porting can protect a valuable mortgage rate and reduce or avoid an early repayment charge, but it is a new lending decision, not an automatic entitlement. A named adviser can look at the full cost, lender criteria and timing of your move, then explain the choices in plain English.
Before you make an offer, speak to an adviser who can check your eligibility and model the options around your real circumstances. A clear answer early on can give you more confidence to move when the right home comes along.