Porting a mortgage UK: can you take your deal with you?

If you've found your next home but you're still tied into a fixed-rate deal, porting a mortgage could let you take your existing rate with you rather than paying an early repayment charge that can run into thousands of pounds. It's one of the first questions worth asking when you start planning a move, alongside how much you can borrow and when to get a mortgage in principle.

This guide covers how porting actually works, who qualifies, what it costs when you borrow more or less than your current balance, and how it compares with remortgaging or a product transfer, so you can weigh up the right route for your move with a clear picture of the trade-offs.

Porting means transferring your current mortgage deal, not the loan itself, to a new property with the same lender. You're not carrying a debt across in the way you might assume: you close your existing mortgage and open a new one with the same lender, on the same rate and terms, secured against your new home.

This is different from switching to a different lender entirely, which is usually done to access a better deal or release equity, or from staying with your existing lender on a new deal without moving home. Mortgage portability only works if your existing lender agrees to carry your current deal forward to the new property.

Not every mortgage is portable, and having a portable product doesn't guarantee approval, since any port is subject to lender approval at the time you apply. Your lender reassesses your income, credit history, and the new property before agreeing, so it's worth checking your mortgage offer or terms and conditions before you get too far into planning your move.

Porting follows the same broad shape as any new mortgage application, but because you're staying with your existing lender, some of the underwriting can move a little faster. Most lenders also build in a grace period between selling your current home and completing on the new one, typically somewhere between 30 and 180 days, which gives you some breathing room if your chain slips.

Eligibility for porting is assessed fresh every time, and it's never guaranteed just because your current deal allows it. Your lender looks at five main factors when deciding whether to carry your mortgage forward to a new property.

If your new home costs more than your current property, you can usually port the existing balance and add a top-up loan for the difference. The two amounts are treated as separate products on one mortgage account, each with its own rate, term, and end date, even though you make one combined monthly payment.

As an illustrative example only, say your current balance is £150,000 on a fixed deal, and your new home costs £275,000. You'd port the £150,000 on your existing terms, and apply for an additional £125,000 as a new product priced at whatever your lender is offering new borrowers at the time. Actual figures depend on your circumstances and what's available when you apply.

If your new home costs less than your outstanding balance, you can't always port the full amount. As an illustrative example, say your existing balance is £200,000 but your new property is worth £150,000. The £50,000 shortfall is effectively repaid early, and that portion is likely to trigger an early repayment charge under your original mortgage offer.

As a further illustrative example, an early repayment charge of 1% applied to a £50,000 shortfall works out at £500, while a charge of 3% on the same shortfall would cost £1,500. Whether porting still makes sense depends on how that figure compares with the interest you'd save by keeping your existing deal, so check the early repayment charges schedule in your original offer before committing to a smaller property.

Porting, remortgaging, and a product transfer solve different problems, and the cheapest option depends on your early repayment charge, your current deal, and what else is on the market. Here's how the three compare when you're moving home.

Porting tends to work out cheaper when your early repayment charge is high and your current deal beats what else is on offer. A product transfer suits homeowners who aren't moving and simply want a new deal without a full application. Remortgaging tends to make more sense when the gap between your rate and the current market is small, or when a different lender can offer something yours can't, such as a higher loan-to-value.

For a full breakdown of remortgaging against a product transfer if you're not planning to move, or to check when it's worth remortgaging instead of porting, it's worth comparing all three before you decide.

Equity is released through the sale and purchase of your properties, not through the port itself. Porting only carries your mortgage rate and terms across to the new property; it doesn't touch the proceeds from selling your current home.

If you sell your current home for more than you owe on your mortgage, that difference is your equity, and it's typically used as part or all of the deposit on your new property. The size of your deposit affects the loan-to-value on the ported balance, which in turn can affect whether the new property meets your lender's lending criteria.

If you're in negative equity, meaning you owe more than your current home is worth, porting can be blocked entirely, since there's no equity to put toward the new purchase and your lender is unlikely to agree to a loan-to-value higher than its current policy allows. In this situation, it's worth speaking to an advisor about your options well before you put your home on the market.

Porting isn't automatically the right choice just because it's available. Here's how the main advantages stack up against the trade-offs before you decide.

If your current deal is well below what's currently available and your early repayment charge would be substantial, porting is usually worth exploring first. If the gap is small, or your circumstances have changed since you took out the mortgage, comparing the wider market with an advisor can show whether switching lender makes more sense for your move.

Yes. Porting still means reapplying for a mortgage, so your lender reassesses your income, credit history, and the new property from scratch. Being accepted for your original loan doesn't guarantee approval for the ported version.

Common reasons a lender might refuse to port a mortgage include:

• Reduced income: your earnings have fallen, or your outgoings have increased, since your original application
• Recent self-employment: you've moved into self-employment and don't yet have two years of accounts
• Higher loan-to-value: the new property needs more borrowing relative to its value than your lender's current policy allows
• Non-standard property type: ex-local authority flats, high-rise buildings, or non-standard construction can fall outside lending criteria
• A deteriorated credit profile: missed payments or new credit issues since you took out the mortgage

Timing can also cause problems if your sale and purchase don't complete on the same day, since most lenders only allow a limited grace period between the two.

If your lender declines to port your mortgage, you still have options. You could pay the early repayment charge and remortgage with a new lender, explore adverse credit mortgage options if your credit history is the sticking point, or in some cases use a bridging loan to cover a short timing gap, though this tends to be an expensive last resort. Your home may be repossessed if you do not keep up repayments on your mortgage or any other debt secured on it, so any borrowing used to bridge a gap needs careful thought before you commit.

If you're worried about how a change in circumstances might affect your ability to port or remortgage, free and impartial guidance is available from MoneyHelper on 0800 138 7777.

Porting is rarely free. It avoids the early repayment charge on the balance you carry across, but several other costs still apply, and they're worth budgeting for alongside the wider costs of moving home.

• Valuation fee: your lender needs to value the new property, even though the mortgage product itself isn't changing
• Legal and conveyancing fees: you still need a solicitor for the purchase, search fees, and registering the new mortgage
• Early repayment charge on any shortfall: only applies if you're porting less than your full balance
• Arrangement fee on top-up borrowing: the new portion is usually priced with its own product fee, separate from the ported balance
• Advice fees: some advisors charge a fee for arranging porting, though this varies by firm

Porting can be worth exploring when your current rate is well below what's currently available and the early repayment charge for leaving early would be costly. But it's never guaranteed: your lender reassesses your income, credit history, and the new property every time, and there are cases where remortgaging or a product transfer works out cheaper once you add up the full picture.

Your home may be repossessed if you do not keep up repayments on your mortgage or any other debt secured on it, so affordability on the new property matters more than which route gets you there. An advisor can compare porting against remortgaging and a product transfer before you commit, so you go into your move with the full picture rather than relying on your existing lender's offer alone.