Each option from the house comparison, explained in detail. Why each won or lost, the transaction calendar, and the Stamp Duty math.
This is the option the comparison landed on. The cleanest tax position, one mortgage, and an end-to-end transaction that lands inside what your income can service. Click the option tabs below for the why on each option.
This is the cleanest tax path. One main home throughout. Principal Private Residence Relief means zero Capital Gains Tax on the sale of your current home because it's been your main residence. Stamp Duty Land Tax on the £750k new purchase comes in at the standard residential rate — not the higher second-home rate.
Equity released from current home: £550k value minus £250k outstanding mortgage = £300k. Add your £100k savings, minus roughly £30k in legal fees, agent fees, moving costs = £370k cash in. New mortgage needed: £750k minus £370k = £380k (or up to £450k if you also fund the Stamp Duty from the loan).
On £130k household income, a £450k mortgage is 3.5× your income — well inside FCA affordability rules (which generally cap at 4.5×).
You now own two homes on completion day, which triggers the Additional Dwelling Supplement — a 5% Stamp Duty surcharge on the entire purchase price, not just the bit above £250k.
You also have two mortgages now — the new home at ~£650k (no equity released) plus the old home remortgaged as a buy-to-let at ~£250k. Combined exposure: £900k. On £130k income that's 7× income, which most lenders won't approve, and a household will struggle to service.
Section 24 (Finance (No. 2) Act 2015, fully effective since 2020/21) makes higher-rate landlords' rental income economically poor: you can no longer deduct mortgage interest from rental profit before paying tax — instead you get a 20% basic-rate credit. On gross rent of £24k/yr, after expenses and Section 24 effects, your real after-tax net is roughly £2–£3k a year on £550k of trapped equity. That's a poor return for the risk.
Plus future Capital Gains Tax exposure: when you eventually sell the buy-to-let, only the years it was your main home get Principal Private Residence relief — the buy-to-let years are taxable.
A closed bridging loan of ~£500k for 6–12 months while your current home goes through the chain. 2026 rates: 8–11% per year, plus 1–2% arrangement fee. Six months at 9% on £500k = £22,500 interest plus £5,000 arrangement = £27,500 cost.
You initially pay Stamp Duty Land Tax with the 5% Additional Dwelling Supplement (£62,500), but you can reclaim the £37,500 surcharge within 12 months of selling your old main home, provided the sale completes within 36 months of the new purchase. End-state Stamp Duty matches Option A's £25k.
When this is worth doing: real risk of a chain collapse on a property you genuinely want. You're paying £27.5k of insurance against losing the new house.
The risk: if the housing market wobbles and your current home doesn't sell within 36 months, you can't reclaim the surcharge — you'd effectively pay Option B's Stamp Duty bill.
Don't move now. Save aggressively (on £130k income, £25–35k/year of savings is realistic), watch interest rates, wait for the kids' school years to stabilise.
In 2028–29 you'd have £175–£200k in savings, your current home will have appreciated (rough 3%/yr), and the £750k house will also have moved. The new mortgage requirement might be £350k instead of £450k.
The question worth asking: could a £100k extension to your current home solve the underlying space problem for a quarter of the cost of a full move? An extension keeps Principal Private Residence Relief and avoids Stamp Duty entirely.
This option is the cheapest by far if the goal is "more space" rather than "different area".
The figures here use the sample profile. When sonuswealth launches, your version uses your real balances and the latest UK rules, updated nightly.
Join the waitlist →Information and guidance only. Not regulated financial advice. For your actual situation, run the live generator on the comparison page or speak to an FCA-authorised adviser.