What Porting a Mortgage Actually Means

Porting is the process of moving your existing mortgage deal from one property to another when you buy a new home. Instead of repaying the loan and starting fresh, your lender agrees to transfer the same terms, rate and remaining term to the new property. In practice, it feels like a halfway house between staying put and remortgaging: you keep the deal you signed up for, but the security for that loan changes from your old address to your new one.

It is important to understand that porting is not an automatic right. Your mortgage contract may include a "portability" feature, but the lender still has to approve the new property and reassess your circumstances. They will look at the value of the new home, your income, your outgoings and your credit file, much as they did when you first applied. If any of those have shifted since your original application, the lender may offer you a different deal or decline the port altogether.

Why Porting Can Save You Money

The main attraction of porting is straightforward: if your current rate is lower than what is available on the market today, you want to keep it. Five-year fixes taken out when rates were near historic lows, for example, can look extremely attractive compared with current pricing. Porting lets you carry that rate over to your next home, so your monthly payments stay predictable.

There is another, less obvious benefit. Most fixed-rate mortgages carry an early repayment charge (ERC) if you pay them off before the deal ends. These charges are typically calculated as a percentage of the outstanding balance, often between 1% and 5%, and can run into thousands of pounds. Porting usually avoids the ERC because you are not actually redeeming the loan; you are moving it. If you are mid-way through a fixed term, that saving alone can be worth more than any arrangement fee.

However, porting is not free. You will usually pay an arrangement fee for the new mortgage, plus valuation and legal costs, because the lender needs to assess the new property and your solicitor has to handle the change of security. Always ask for a full breakdown of fees before you commit.

How the Porting Process Works Step by Step

• Check your deal allows it. Look at your original mortgage offer or key facts document, or call your lender. Not every product is portable, and some deals lose portability if you have already switched to a follow-on rate.
• Get an agreement in principle early. Before you make an offer on a new home, ask your lender to confirm they would consider porting. This gives you confidence when estate agents ask how you are funding the purchase.
• Submit a full application for the new property. The lender will value the new home and reassess your affordability. If the new property is worth more than the old one, you will need to cover the difference through a larger deposit, additional borrowing or a second charge.
• Coordinate the timing. This is the tricky part. You need to sell your old home and buy the new one, and your lender needs to release the charge on one property and register it on the other. Bridging finance or a short rental period may be needed if the dates do not align.
• Complete the legal work. Your solicitor will handle the discharge of the old mortgage and the new charge, and you will sign a new mortgage deed. Expect the lender's valuation fee and your legal fees to fall due around this point.

The Common Stumbling Blocks

Porting sounds tidy on paper, but a few things often trip people up. The first is affordability. If your income has fallen, your debts have grown, or the new property is more expensive, the lender may only offer to port part of the loan and ask you to take out additional borrowing at a different rate. That creates a "split" mortgage, and you need to weigh up whether the blended rate is still better than remortgaging entirely.

The second is timing. Lenders typically give you a window to port, often three to six months, and if your sale falls through or your purchase drags on, you can breach the deadline. Some lenders will extend it, but not all. If the window closes, you may be forced onto the standard variable rate or hit with an ERC.

The third is the property itself. Lenders have criteria on construction type, lease length, location and condition. A home that you love might not meet their security requirements, particularly if it is a non-standard build, has a short lease or sits above commercial premises. Checking this before you instruct solicitors saves a lot of heartache.

Porting Versus Remortgaging: How to Choose

The decision usually comes down to maths and timing. Porting makes most sense when your existing rate is comfortably below current market rates, when you are still inside a fixed term with a hefty ERC, and when your circumstances have not changed much. Remortgaging makes more sense when your current deal is ending soon, when the ERC has expired, or when a new lender is offering a rate that is low enough to offset any fees and charges.

It is worth getting both figures in front of you: the total cost of porting, including fees and any extra borrowing, against the total cost of a fresh mortgage. A whole-of-market broker can run these comparisons quickly and will know which lenders are flexible on timescales and criteria.

Practical Tips Before You Commit

Start the conversation with your lender as soon as you decide to move, ideally before you put your home on the market. Keep your paperwork in order: payslips, bank statements, proof of deposit and details of any other debts. Avoid taking on new credit in the months before you apply, because it can affect the affordability assessment.

Finally, read the small print on your original offer. Check whether porting is guaranteed or at the lender's discretion, whether the arrangement fee is charged again, and how long you have to complete. A little preparation now means you keep the deal you worked hard to secure, and your move stays on track.