Moving house with a mortgage is rarely as simple as packing boxes and forwarding the post. Your existing mortgage doesn’t automatically transfer with you, and the choices you make at this stage can cost or save you thousands over the life of the loan.
If you’re a homeowner thinking about your next move, our guide explains exactly how a mortgage works when moving house, the three main routes available to you, and how a mortgage broker can help.
How does a mortgage work when moving house?
When you move house, you have three main options for your mortgage:
- Port your existing mortgage to the new property
- Repay your current mortgage and take out a brand-new one
- Keep the old mortgage as a let-to-buy and add a new one for your next home
While, commonly most movers focus on the first two, deciding which route is right for you depends on your current deal, early repayment charges (ERCs), the amount you need to borrow, and where rates sit when you move.
Remember, your mortgage is tied to a specific property, not to you and selling that property triggers a decision about what happens to the loan secured against it.
What is porting a mortgage?
Porting a mortgage means transferring your existing mortgage deal – the same interest rate, terms and conditions – from your current home to your new one. You’re not literally moving the loan, you’re repaying the old mortgage on completion of your sale and taking out a new one with the same lender on the same terms.
Porting is attractive when:
- You’re locked into a competitive fixed rate that’s lower than what’s currently available
- Leaving your deal early would trigger significant early repayment charges (typically 1–5% of the outstanding balance)
- You want continuity and minimal disruption
However, porting is not guaranteed, even if your lender’s product is “portable” on paper. You’ll need to reapply and pass affordability checks under current criteria, which since the FCA’s Mortgage Market Review and subsequent stress-test rules tend to be stricter than when you first borrowed. Lender criteria also tighten and loosen over time, so an application that passed in 2022 may look different in 2026.
How does porting a mortgage work?
Here’s the typical process for moving a mortgage to a new house via porting:
1. Speak to your lender or broker early, ideally before you put your home on the market. You need to know whether your deal is portable and what your borrowing capacity looks like today.
2. Reapply for the mortgage. Even though it’s the same product, the lender treats it as a fresh application. Expect income verification, credit checks, and a property valuation on the new home.
3. Time the sale and purchase, as most lenders require completion of your sale and purchase on the same day, or within a short window, commonly up to 30 days (though some allow up to 180 days).
4. If the new property costs more, you can usually borrow additional funds. The top-up is typically taken on a separate product at current rates, meaning you may end up with two sub-accounts on one mortgage – sometimes called a “split” or “part-and-part” arrangement.
5. Complete on both transactions. Your solicitor coordinates the redemption of the old mortgage and drawdown of the new one.
What if I’m borrowing more for the new house?
Most people moving up the ladder need to borrow more. Porting handles this through a top-up loan at the lender’s prevailing rates. You keep your existing balance on the old (often better) rate, and the additional borrowing sits on a new product alongside it.
However, the downside is that you can end up with two end dates and two ERC periods running concurrently, which complicates any future remortgage. A broker will model this against the alternative, paying the ERC, leaving the deal entirely, and starting fresh, to show you the true cost difference.
What if I’m borrowing less or downsizing?
If you’re downsizing or borrowing less, porting still works but you may face a partial early repayment charge on the amount you’re no longer borrowing. For example, port £200,000 of a £250,000 mortgage and the lender may charge ERC on the £50,000 you’ve effectively repaid early. Always ask for this calculation in writing before committing.
Do I need a new mortgage when I move house?
Porting isn’t always the best option – you might be better off paying the ERC and switching to a new mortgage if:
- Current market rates are lower than your existing rate
- Your deal is close to ending, so the ERC is small
- The lender won’t approve the borrowing you need under current affordability rules
- You want to access products (offset, lifetime tracker, longer terms) your current lender doesn’t offer
A fresh remortgage with another lender could leave you better off even after ERCs.
How long does it take to move a mortgage to a new house?
Allow 6 to 12 weeks from application to completion in most cases, broadly the same as a first-time mortgage. Porting can sometimes be slightly faster because the lender already holds your records, but the property valuation, conveyancing and chain coordination still apply.
Start the conversation with a broker as soon as you decide to move. Getting an Agreement in Principle early shows estate agents and sellers you’re serious, and it flags any affordability issues before you waste time on offers you can’t fund.
How a mortgage broker can help
Moving house with a mortgage involves more variables than your first purchase. You’re balancing ERCs, top-up rates, lender criteria, completion timing, and the wider market – often under chain pressure.
A whole-of-market broker like Mortgage Saving Experts compares your existing lender’s offer against the rest of the market and shows you the real cost of each route, including fees. For homeowners, we handle the lender liaison, paperwork and timing so you can focus on the move itself.
Ready to move house?
If you’re planning a house move in 2025 or 2026 and want clarity on whether porting your mortgage or switching to a new deal is right for you, get in touch with our experts for a no-obligation review of your options. We’ll model the numbers both ways so you can move with confidence.
Your home may be repossessed if you do not maintain payments on any mortgage or loan secured on it.
Mortgage Saving Experts Ltd is authorised and regulated by the Financial Conduct Authority FCA number 779662.
