Porting a mortgage: taking your deal with you when you move home

What is porting a mortgage?

Porting a mortgage means taking your current mortgage deal with you when you move home. The interest rate, the date the deal ends and its other terms carry over to a mortgage on the home you are buying, with the same lender. The usual reasons are to keep a rate and to avoid the early repayment charge for leaving a deal before it ends.

"Transfer a mortgage to another property" describes the idea, but not quite what happens. The loan on your old home is repaid when the sale completes, and the lender makes a new loan secured on the new home. What moves across is the deal: the rate and the terms attached to it.

Porting is a feature of a mortgage product: some deals have it, with conditions, and some do not. The mortgage rules of the Financial Conduct Authority (FCA) require the illustration you are given for a mortgage to say whether it can be moved to another property, and on what conditions. The rules set out two formats for that illustration: in one the answer is in the section headed "Flexible features", and in the other it is under "What happens if you move house?". So the answer for your own deal is already in your paperwork.

The guide to the types of mortgage explains the fixed, tracker and discount deals a port can carry.

How does porting a mortgage work?

Moving house with a mortgage follows the same steps as any purchase, with one difference: you apply to the lender you already have.

Where the sale and the purchase complete on the same day, the old loan ends as the new one begins. Where there is a gap, a lender may take the early repayment charge when the old loan is repaid, and whether it refunds the charge once the new mortgage completes, and on what conditions, is set by its terms.

Some lenders give a mortgage in principle before a full application to port.

Can I port my mortgage? The checks a lender makes

Two things decide it: whether your deal is portable, and whether the lender agrees to lend on the new home. A lender generally treats a port as a new mortgage application, decided under the lending policy it has on the day you apply, not the one it had when you first borrowed.

The lender commonly looks at:

• The property. The new home is valued, and it has to be a property the lender accepts as security.
• Your loan to value. This is the loan as a share of the new home's value. A deal is priced for a loan-to-value band, so the ported loan has to fit it.
• Your income and outgoings. How deep this check goes can depend on whether you borrow more, as the next section explains.
• Your credit record and your payment history. The guide to the credit score for a mortgage explains what lenders see.
• Its current criteria. A lender's rules on age, income and property types can change between your first application and your move.

A lender can refuse. The Financial Ombudsman Service, which settles complaints between consumers and financial firms, gives the example of a new home whose value would put the ported balance outside the loan-to-value range for the rate the customer wants to keep.

What the rules say about affordability

The FCA's rules normally require a lender to assess whether you can afford a mortgage before it enters into one. As the rulebook stood in November 2026, that rule does not apply to a new mortgage that replaces an existing one with the same lender, whether or not it is on the same property, if two conditions are met. The first is that you borrow no more than the amount currently outstanding, apart from any product or arrangement fee for the new mortgage. The second is that no term of the mortgage changes in a way that is likely to be material to affordability.

The rules list changes that a lender is expected to treat as likely to be material: a longer term that can be expected to run into, or further into, your retirement, a switch between repayment and interest only, and adding or removing a borrower. The list is not exhaustive.

This is a permission, not an instruction. A lender may agree a like-for-like port without the assessment the rules would otherwise require, but the rules do not stop it making its own affordability checks, and they do not oblige it to lend. It can still decline under its own policy on the property, the loan to value or anything else. The Financial Ombudsman Service tells lenders that it might be unfair to refuse a port on affordability grounds when no further borrowing is involved, and that a lender can refuse on other grounds.

If you borrow more, the exception does not apply, and the FCA's affordability rule applies as it would to any new loan. The guide to mortgage affordability explains what lenders count, and the how much you could borrow calculator gives an illustration.

Borrowing more, the same or less when you port

Few moves need exactly the loan you have now. How a lender handles the difference is its own practice, not a rule, so the arrangements below are common ones that your lender may not follow.

Borrowing more

Extra borrowing is often set up as a separate part of the mortgage, though this varies by lender. It takes a rate from the deals the lender offers on the day, which may differ from the rate you are porting, and it may carry its own product fee. The two parts may end on different dates, which matters later: when the first part's deal ends, the second may still carry an early repayment charge. That can make a later move to another lender harder to time, as the guide to remortgaging explains. The mortgage calculator shows the monthly payment on each part if you enter them one at a time.

Borrowing less

The Financial Ombudsman Service describes an early repayment charge as a fee you might be asked to pay if you want to reduce the amount you have borrowed, which a lender might apply during the term of a fixed, capped or discounted rate. So a smaller loan on the new home can mean a charge on the part you do not take with you. Deals commonly let you repay a limited amount each year without a charge, and whether that allowance can be used on a port varies by lender. The guide to mortgage overpayment explains those allowances.

Do you need a deposit when you port a mortgage?

Yes, in the sense that a lender lends only a share of a home's value and the rest of the price has to come from you. For most movers that is the equity from selling the old home: the sale price less the mortgage repaid and the costs of selling.

What matters to the lender is the loan to value on the new home, which rises if you borrow more or the valuation comes in below the price. The guide to loan to value shows how the bands work.

If you cannot port, or choose not to

When a port is refused, or the deal is not portable, the choices are to stay put, to wait until the deal ends, or to repay the mortgage and borrow elsewhere, which usually means an early repayment charge.

The FCA says the charge is normally a percentage of the remaining mortgage balance and usually falls as the deal nears its end. Under FCA rules it must be able to be expressed as a cash value and be a reasonable pre-estimate of the lender's costs from early repayment, and the maximum charge is set out in your mortgage illustration. The guide to mortgage fees covers the charge and the other costs of leaving a lender.

Some borrowers who plan to move soon let a deal run out and stay on the lender's standard variable rate for a short time, because it usually carries no early repayment charge. The FCA says the rate a deal reverts to is normally higher than the initial rate.

If you think a refusal was unfair, you can complain to the lender, which has eight weeks to give its final response to most complaints. After that you can take the complaint to the Financial Ombudsman Service, which looks at the lender's reasons and at whether it was fair to apply the charge in the circumstances. In one published case study it told a lender to refund the charge where a borrower with a portable fixed rate, who was not borrowing more, was refused because the lender had changed its age limit. In another it did not uphold a complaint from a borrower who wanted to port and borrow more, because the lender had assessed the extra borrowing reasonably and had explained the charge before he committed to buying. These are single decisions, not rules, and each case turns on its own facts.

Porting or a new mortgage: what to compare

Porting keeps the deal you have, which is not the same as costing less than starting again.

The sum sets the early repayment charge and the fees on each route against the difference in interest. The remortgage calculator compares keeping a rate with switching, charges and fees included, and the mortgage rates comparison shows the rates lenders publish today. Both are illustrations, not advice.

A qualified, regulated mortgage adviser can compare a port with a new mortgage for your circumstances. The guide to using a mortgage broker explains how advisers work and how they are paid.

The other costs of moving house with a mortgage

Porting changes the mortgage, not the move: the purchase still has legal and valuation costs, and it is taxed like any other. In England and Northern Ireland the tax is Stamp Duty Land Tax; Scotland and Wales have their own land taxes, with their own rules. GOV.UK says you usually pay 5% on top of the standard rates if buying means you will own more than one residential property, which includes not having sold your main residence on the day you complete the purchase. It says the extra does not apply where the new home replaces your main residence and the previous one is sold within 36 months of completing the new purchase, and it explains how to check for a refund of the higher rates. The stamp duty calculator works out the tax for your price, and the guide to stamp duty on new builds explains the rules.

Porting a mortgage to a new build

Porting to a new-build home works the same way, but the timetable is the builder's.

• The offer has to last. FCA rules require a mortgage offer to state the period for which it is valid. On a home still being built, completion can be many months after you reserve. Whether a lender gives a longer offer on a new build, or extends one, varies by lender.
• The deal keeps running. A long build uses up the time left on your current deal. If the deal ends before the new home is finished, there may be nothing left to port.
• The sale and the purchase may not line up. The builder sets the completion date by the progress of the build, and your buyer may not want to wait. If you sell first and repay the mortgage, the gap described above applies.

The guide to new build mortgages covers offer periods, incentives and the rules lenders apply to new homes.

A checklist before you port

1. Find what your mortgage illustration and offer say about moving home and the early repayment charge.
2. Ask your lender how it handles a port, and what happens if the sale and the purchase complete on different days.
3. Work out the loan you need on the new home and the loan to value it gives.
4. If you need more or less, ask how the extra would be lent, or whether a charge applies to the part repaid.
5. Speak to a qualified, regulated mortgage adviser if you want advice on the decision.

The mortgage hub gathers the calculators, the lenders' published rates and the other mortgage guides.