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Sign in to keep them on every device →Work out stamp duty, the cash you need, yield, cash flow and return for a buy-to-let, HMO, flip or BRRR deal. Open it from any home or postcode to fill in our estimate, the floor area, local rents and Local Housing Allowance. New to these? Read the strategy guides.
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Buy, refurbish, rent, then refinance to pull your money back out. Pre-filled for 18, Swanbridge Road; change anything.
Outer South East London rates, 2026–27, a month: shared room £600 · 1 bed £1,050 · 2 beds £1,300 · 3 beds £1,550 · 4 beds £1,800. The most housing support a tenant on benefits can get here; a guide to the bottom of the market.
| Deposit (30% of price; bridging loan for the rest) | £209,700 |
| Stamp Duty Land Tax (additional-home rates) | £59,900 |
| Legal fees | £1,800 |
| Survey | £600 |
| Bridging fee (2%) | £9,786 |
| Bridging interest (6 months at 0.85% a month) | £24,954 |
| Total cash in | £306,740 |
| £0 – £125,000 | 5% | £6,250 |
| £125,000 – £250,000 | 7% | £8,750 |
| £250,000 – £699,000 | 10% | £44,900 |
Additional-home rates, as checked in October 2026. Buying through a company, or replacing your main home, can change this. Stamp duty calculator
| Rent | £22,380 |
| Mortgage payments (interest only, 5% on £655,500) | −£32,775 |
| Voids (5% of rent) | −£1,119 |
| Letting and management (10% of rent collected) | −£2,126 |
| Repairs and maintenance (8% of rent) | −£1,790 |
| Landlord insurance | −£350 |
| Cash flow before tax | −£15,780 (−£1,315 a month) |
| New mortgage (75% of £874,000) | £655,500 |
| Bridging loan repaid | −£489,300 |
| Cash back out | £166,200 |
| Money left in the deal | £140,540 |
Return on the money left in: -11.2% a year.
Lenders usually test the rent against interest at a higher “stress” rate, here 7%. Rent covers it by 125% (basic-rate taxpayers and companies): no; by 145% (higher-rate taxpayers): no. The rent supports a loan of about £255,771 or £220,493. Lenders differ.
All figures are before income tax. Individual landlords cannot deduct mortgage interest in full (they get a 20% tax credit instead), so higher-rate taxpayers pay tax on more than their cash flow. This is a calculator, not financial advice. Read the guide