Trading up to a more expensive home is exciting, but it means a bigger mortgage and higher costs, so it pays to understand what is involved. This guide explains moving to a more expensive home: topping up your mortgage, how much you can borrow, the stamp duty, and keeping it affordable.
Topping up your mortgage
Moving to a dearer home usually means increasing your mortgage to cover the higher price, after the equity from selling your current home is taken into account. You can do this by porting your existing deal and adding a top-up, or by taking a larger new mortgage, as our guide to borrowing more when you move explains. Either way, your mortgage grows to bridge the gap between your equity and the new price.
How much more you can borrow
How much more you can borrow depends on your income, outgoings and the lender's affordability rules, much as it did when you first bought. The equity from your current home plus the additional borrowing determine the price you can afford. It is worth working out your borrowing capacity early, so you house-hunt within budget. Trading up is constrained by affordability, not just by your wish for a bigger home.
Porting plus a top-up
If you have a good rate, porting your deal and borrowing the extra as additional borrowing lets you keep that rate on your original balance while taking a top-up for the difference, as our guide to porting explains. The top-up may be at a current rate, possibly different from your ported deal. This can be cost-effective when your existing rate is worth keeping, though it is worth comparing against a full new mortgage.
Stamp duty on the higher price
A more expensive home means more stamp duty, because the tax is charged in bands that rise with the price, as our guide to moving and stamp duty explains. Since April 2025, standard rates apply above £125,000, rising through 5% above £250,000 and higher bands beyond. The dearer your new home, the larger the stamp duty bill, so it is an important cost to budget for when trading up.
Affordability and stress testing
The lender will assess whether you can afford the larger mortgage, including stress testing against higher interest rates. Borrowing more means bigger payments, so it is important the new mortgage sits comfortably within your budget, not just that you can get it. Trading up to the maximum you can borrow can leave you stretched, so consider what monthly payment you are comfortable with rather than simply the largest mortgage available.
The cost of a bigger mortgage
A larger mortgage means higher monthly payments and more interest over the term, sometimes substantially more. It is worth weighing the benefit of a bigger or better home against this ongoing cost, and considering whether a slightly less expensive home would leave you more comfortable. Trading up is a balance between the home you want and the cost of financing it, so a clear view of the monthly cost helps you decide.
Budgeting for the whole move
Beyond the mortgage and stamp duty, trading up brings the usual moving costs: legal fees, a survey, estate agent fees on your sale, removals and possibly mortgage fees. These add to the cost of moving up. Budgeting for the whole move, alongside the larger mortgage and higher stamp duty, ensures you can afford not just to buy the more expensive home but to complete the move comfortably.
An example of trading up
Suppose you sell a £250,000 home with a £120,000 mortgage, leaving £130,000 of equity, and buy a £400,000 home. You put in your equity and borrow £270,000. On top of the larger mortgage, you would pay stamp duty on the £400,000 purchase under the standard bands, plus legal fees, a survey and removals. Seeing the full picture, mortgage, stamp duty and costs, helps you judge whether the move is affordable.
Using the equity from your sale
The equity from selling your current home is central to trading up, as it forms the deposit on the new one. The more equity you have, the less you need to borrow for a given new home, or the more expensive a home you can afford for a given mortgage. Working out your likely equity, after repaying your current mortgage and paying selling costs, is the starting point for planning a move up.
Do not forget the running costs
A bigger or better home often costs more to run, with higher council tax, energy bills, insurance and maintenance, as well as a larger mortgage. These ongoing costs matter as much as the purchase, since they affect whether you can comfortably live in the home long term. Considering the full running cost of a more expensive home, not just the mortgage, helps ensure trading up is sustainable for your budget.
Borrowing comfortably, not to the max
It is tempting when trading up to borrow as much as possible for the best home you can get, but borrowing to your limit leaves little room if rates rise or your income changes. Choosing a mortgage whose payments are comfortable, even if it means a slightly less expensive home, protects you against the unexpected. A comfortable mortgage on a good home usually beats a stretched one on a perfect home.
Planning the whole budget
Trading up succeeds when you plan the whole budget: the deposit from your equity, the larger mortgage, the stamp duty, and all the moving costs, with a buffer for surprises. Laying out every figure shows whether the move is affordable and avoids a late shortfall. Approaching a move up the ladder with a complete budget, rather than focusing only on the new mortgage, makes the whole process far less stressful.
Trade up with your eyes open
Trading up to a better home is one of the rewards of owning property, but it works best when done with your eyes open to the full cost. A bigger mortgage, more stamp duty, higher running costs and the expenses of moving all add up. By planning the complete budget, borrowing comfortably rather than to the limit, and weighing the benefits against the costs, you can move up the ladder in a way that improves your life without overstretching your finances.
Make sure the move is worth it
Before committing to a more expensive home, it is worth pausing to make sure the move is genuinely worth the extra cost. A larger mortgage, more stamp duty and higher running costs are a long-term commitment, so the benefits, more space, a better area, or a home you will be happy in for years, should justify them. When the move clearly improves your life and the numbers comfortably work, trading up is a sound decision rather than a financial stretch.
In short
Moving to a more expensive home means a bigger mortgage, achieved by porting and topping up or by taking a larger new mortgage. How much more you can borrow depends on affordability, and a dearer home brings more stamp duty under the bands that apply since April 2025. Borrow a comfortable amount rather than the maximum, weigh the cost of a bigger mortgage, and budget for the whole move.
Where to get help and next steps
Read our guides to borrowing more when you move, moving home and your mortgage, and downsizing. This is general information, not mortgage or financial advice.