Moving Home: Should You Port Your Mortgage or Get a New One?

If you already have a mortgage and you are planning to move home, you face a decision most first-time buyers do not: what to do with your existing mortgage. Can you take it with you? Should you? Would you be better off on a completely new deal? In this guide, I explain exactly how mortgage porting works, when it makes financial sense, what early repayment charges mean for your timing, and how to manage the complexities of buying and selling simultaneously.

Can I take my existing mortgage with me when I move house?

Potentially — if your mortgage is portable. Most standard residential mortgages include a portability feature, which means you can transfer the existing mortgage (with its current rate and remaining term) to a new property. However, portability is not guaranteed, and even if your mortgage is portable, porting it may not always be the right financial decision.

To port your mortgage, your lender will carry out a full reassessment of your financial situation — income, outgoings, credit profile — as if you were applying for a new mortgage. They will also conduct a valuation of the new property. Even with a portable mortgage, there is no guarantee the lender will approve the port if your circumstances have changed materially since you originally took it out.

What is porting a mortgage and how does it work?

Porting means transferring your existing mortgage deal to a new property, keeping the same interest rate, product type, and remaining term. You are, in effect, swapping the security from one property to another while keeping everything else the same.

The process typically works as follows:

1. You apply to your lender to port the mortgage to the new property
2. The lender reassesses your affordability based on your current circumstances
3. They conduct a valuation of the new property
4. If approved, you repay the existing mortgage on your sale (using sale proceeds) and simultaneously take out the ported mortgage on your new purchase

The timing of the simultaneous sale and purchase is critical, and any gap between completing on the sale and completing on the purchase needs to be managed carefully — particularly if you want to avoid a period where you technically have no mortgage and have repaid the original, potentially losing the opportunity to port.

Will I have to reapply for my mortgage if I move home?

Yes — even if you are porting. The lender is applying their current affordability assessment to your current financial situation, not relying on their original approval from several years ago. Your income, outgoings, and credit profile will all be reassessed against current underwriting criteria.

This matters if your circumstances have changed. If your income has increased substantially, you may be able to borrow significantly more than your original mortgage. If you have taken on significant additional commitments — car finance, higher mortgage payments on other properties, changes to credit utilisation — the lender may approve the port on the original amount but decline to increase it.

What happens if I need to borrow more when I move to a more expensive property?

This is very common — most people moving home are upsizing. If you want to borrow more than your existing mortgage balance, there are a few options:

Additional borrowing with the same lender: Many lenders will allow you to port the existing mortgage and take a top-up loan for the additional amount needed. The top-up is typically on a new product at the current market rate — so you end up with two separate loan parts running simultaneously: your original ported product and the new top-up product.

Full remortgage to a new lender: Sometimes it makes more financial sense to pay off the existing mortgage (potentially including an early repayment charge) and take an entirely new mortgage on the new property for the full amount needed. If current market rates are competitive against your existing rate and the additional borrowing is substantial, the ERC may be justified by the better overall deal available.

We calculate both options with actual numbers before recommending either. The right answer depends on: your current rate, the ERC, how much additional borrowing you need, and what rates are available for the full amount from across the market.

Will I face an early repayment charge if I move before my fixed rate ends?

If you are porting your mortgage to the new property, you should not face an ERC — you are continuing the same mortgage, not ending it. The product transfers from one property to the other.

However, ERCs can arise in moving scenarios in two situations: first, if you are unable to port and need to repay the mortgage early (breaking the fixed term before porting can be completed); and second, if you want to take a completely new mortgage rather than port, forcing an early repayment of the existing deal.

ERCs are typically a percentage of the outstanding loan balance, reducing year by year through the fixed period. On a £300,000 mortgage, a 2% ERC is £6,000. Whether paying this is justified depends entirely on what you gain by switching versus what you save by porting — a calculation we make with every home mover client.

How does the equity in my current home affect what I can borrow?

Equity is the difference between your property's current value and the outstanding mortgage balance. When you sell, the equity is released as cash — which you can put towards the deposit on your next purchase.

The more equity you have, the lower the LTV on your next mortgage, which typically means access to better rates and a wider choice of lenders. For home movers who bought several years ago and have seen property values rise, the equity position is often significantly better than they realise — and this can transform the range of mortgage products available to them on the next purchase.

We always calculate the expected net equity from the sale (selling price minus outstanding mortgage, minus estate agent fees, minus solicitor costs) as part of mapping out the financial picture for a home move.

What if my new property is worth less than my outstanding mortgage?

This is known as negative equity — owing more on your mortgage than the property is worth. It is relatively uncommon for existing homeowners but can occur in areas where property values have fallen since purchase, or where significant additional borrowing was taken.

Moving home in negative equity is very difficult — most lenders will not allow you to port a mortgage to a new property if the existing security is in negative equity, because you have no equity to contribute to the new purchase. It typically requires either waiting for values to recover, making overpayments to reduce the balance, or negotiating with the lender on an individual basis.

If you are concerned you might be in or near negative equity, a conversation with a broker who can assess your position honestly is the right first step.

What if there is a gap between selling and buying?

In an ideal world, your sale and purchase complete on the same day and there is no gap. In practice, chains shift, legal delays happen, and the two transactions do not always align perfectly.

If your sale completes before your purchase does — and you need to repay your mortgage on the sale — you may need bridging finance to fund the purchase of the new property until the sale funds are available. This is one of the most common residential uses for bridging loans, and we arrange regulated bridging finance as part of our service*. See our Bridging Loans guide for full details.

*This service is offered by a trusted third-party.

Alternatively, some buyers complete the sale and move into rental temporarily while their purchase progresses — less expensive than bridging finance if the timeline is uncertain, but more disruptive.

How long does it take to get a mortgage when moving home?

A porting application — if straightforward and with a lender who holds your existing file — can move quickly, sometimes in two to three weeks. A new mortgage with a different lender follows the same timeline as a standard application: typically four to eight weeks from application to offer, then the legal process until completion.

The key practical message: do not leave this until your property is already under offer. Contact a broker as early as possible in the process — ideally while you are still preparing to put your home on the market. Knowing what you can borrow helps you search in the right price range, and having finance in place makes you a more credible buyer when you put in an offer on your next property.