What is Porting a Mortgage?

How Porting Works in Practice

Porting is a product feature on many mortgages; this means that you are not transferring the original loan itself, but rather you are reapplying to use the same rate and terms on a different property. The lender reassesses you as if you were a new applicant and then, if approved, they apply your current deal to the new loan amount. If you need to change the balance, the lender combines your ported deal with additional borrowing or a partial repayment as required.

A typical porting process might look like this:

1. Check your current mortgage is portable and note any Early Repayment Charges and dates.
2. Speak to your lender or a broker to check affordability and eligibility for the new property.
3. Provide documents, then the lender values the new home and underwrites the case.
4. If approved, the lender issues a new offer showing the ported rate and any extra borrowing on a separate product.
5. On completion, your old mortgage is redeemed, and the new borrowing starts on the new property.

Eligibility and Lender Checks

Most, but not all, residential mortgages are portable. Your original offer or product factsheet will usually outline whether porting is allowed. Even if the existing mortgage can be ported, approval depends on a full reassessment against today’s criteria, not the rules in place when you first applied.

Expect the lender to test affordability based on your income, spending and credit history. They also look at stability, such as employment type and length of service, or proof of self-employed income. Property checks include a valuation, standard construction, condition and likely resaleability. They will also assess loan-to-value, any loan size caps and whether the remaining term is suitable.

If your circumstances have changed, such as a reduction in income, recent credit issues or higher non-mortgage commitments, the lender may decline to port the mortgage or limit any extra borrowing. In that case, choosing a new lender may still be an option.

Home Moving Scenarios

If you are planning a move and weighing up your choices, our home mover mortgage advice explains how porting sits alongside other routes and how we support timing and criteria decisions: Home mover mortgages

Borrowing the Same Amount

This is the cleanest outcome. You port your existing balance to the new home on the same rate and remaining fixed or tracker period. Because the overall loan does not change, Early Repayment Charges are usually avoided, although standard fees such as valuation and legal costs can still apply. Your monthly payment may change slightly if the completion date adjusts your remaining term.

Borrowing More to Upsize

If you need a bigger mortgage, the lender typically splits the borrowing. Your current balance ports to the new home on your existing product, while the top-up sits on a new product at a rate available today. The two parts can have different rates and end dates. You may face a product fee for the new part, and affordability must cover the combined payment. If the loan-to-value on the overall borrowing rises, it can affect both pricing and the lender’s decision.

Borrowing Less or Moving to a Cheaper Property

Downsizing can trigger partial Early Repayment Charges because you are repaying part of the loan during a tie-in. Many mortgages allow up to a 10 per cent annual overpayment without charge, but rules vary by lender and by product. If you repay more than the allowance when you move, the lender can apply an ERC on the excess. Some lenders will let you reduce the ported amount within certain limits without a fee; others will not. Work out the figures before you list your home so the net effect is clear.

Early Repayment Charges

An Early Repayment Charge, or ERC, is a fee for repaying some or all of your mortgage during a fixed or discounted period. With porting, the ERC risk arises either if you pay off the loan and do not complete a port to a new property, or if you reduce the balance by more than any permitted allowance.

If your sale and purchase happen on the same day, the lender can usually transfer your current deal directly, and no ERC is taken. If you sell first, the lender may charge an ERC on redemption, then refund it if you complete a qualifying port to a new home within a set window, commonly around six months, though the timeframe and conditions differ by lender. Ask for the refund rules in writing.

ERCs are usually a percentage that tapers each year, for example, 3 per cent in year two, 2 per cent in year three. The calculation and timing matter, so confirm the exact figure and whether any overpayment allowance applies to a partial balance reduction linked to your move.

Costs to Budget for

Porting can still involve fees, even if you avoid an ERC. Customers should create a budget for:

• Valuation fee for the new property.
• Product fee for any extra borrowing.
• Lender administration or transfer fee.
• Conveyancing costs for sale and purchase.
• Potential arrangement or booking fee if applicable.

Ask for a full cost illustration so you can compare porting with switching lenders on a like-for-like basis. If you want to explore a fresh deal across the market, see our remortgage advice to understand timings, fees and product choices.

Porting versus Remortgaging

Porting keeps your current rate if the lender agrees to the move. Remortgaging means taking a brand new deal, usually with a different lender, and paying any ERC due on the old mortgage.

The key difference is control. Porting can be cost-effective if your current rate is competitive and ERCs are high. However, remortgaging might win out if your existing rate is uncompetitive and the savings offset any fee to exit.

When Porting May Not Suit You

If your income has fallen or your credit has worsened since you last applied, your lender may reject the port even if the mortgage is technically portable. A new lender with different criteria might still say yes. Porting can also be less attractive where the existing rate is far above today’s best options or where you need large additional borrowing that would sit at a much higher rate, making a clean, single new deal simpler. Non-standard properties that your current lender will not accept, for example,, certain types of construction or flats above commercial premises, can also block a port.

Sale and Purchase Timing

Many movers sell first, then buy. In that case, your old mortgage is redeemed, and an ERC may be charged on completion. If your lender allows it and you complete the new purchase within their permitted window, they can refund the ERC once the port is finished. Keep proof of the date range and conditions, and plan for temporary housing or short-term finance carefully. Rate locks and offer expiry dates matter, as do changes to your circumstances while you are between homes.

Special Situations to be Aware of

Porting part of a mortgage is common when downsizing, but it can introduce different end dates on split parts of the new loan. Some borrowers move from a joint mortgage to a sole mortgage, or the other way round. That change triggers fresh affordability and credit checks for all named borrowers. If you are converting a residential mortgage to buy to let at the same time as moving, most lenders treat this as a different product type rather than a port. For guidance on options and criteria, see our page on buy-to-let mortgages in Huddersfield. Finally, if your current product is close to its end date, a short wait may remove the ERC entirely, so timing can be a material decision factor.

Speak to a Mortgage Adviser

Porting decisions hinge on detail: ERCs, split borrowing, criteria and timing. If you want a clear view of your options before you list your home, speak to a mortgage adviser at Mortgage To Home. Visit the Mortgage To Home homepage to arrange a chat and weigh porting against a new deal in your circumstances.

Your home may be repossessed if you do not keep up with repayments on your mortgage.