Deal calculator

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.

Buy a home and let it to one household. Pre-filled for Flat 11, 1, Carlos Place; change anything.

−£10,417Cash flow a month

0.8%Net yield

-7.3%Return on cash

The homePurchase priceour estimate today; use the asking priceWhereRefurbishment177 m² (1,905 sq ft) floor area, energy rating D

Rough 2026 starting points, not quotes.

Buying costsLegal feesSurveyOther

MortgageLoan to value%Interest rate%Lender and broker feesType

LettingRent a monthcouncil average for 3-bed homes (ONS); 4 rooms on the energy certificateVoids%Letting and management%Repairs and maintenance%Insurance a yearService charge and ground rent a year

Local Housing Allowance here

Central London rates, 2026–27, a month: shared room £830 · 1 bed £1,440 · 2 beds £1,794 · 3 beds £2,160 · 4 beds £3,060. The most housing support a tenant on benefits can get here; a guide to the bottom of the market.

Cash in

Deposit (25% of price)	£1,072,500
Stamp Duty Land Tax (additional-home rates)	£643,050
Legal fees	£1,800
Survey	£600
Total cash in	£1,717,950

Stamp Duty Land Tax: £643,050

£0 – £125,000	5%	£6,250
£125,000 – £250,000	7%	£8,750
£250,000 – £925,000	10%	£67,500
£925,000 – £1,500,000	15%	£86,250
£1,500,000 – £4,290,000	17%	£474,300

Additional-home rates, as checked in October 2026. Buying through a company, or replacing your main home, can change this. Stamp duty calculator

A year of letting

Rent	£46,740
Mortgage payments (interest only, 5% on £3,217,500)	−£160,875
Voids (5% of rent)	−£2,337
Letting and management (10% of rent collected)	−£4,440
Repairs and maintenance (8% of rent)	−£3,739
Landlord insurance	−£350
Cash flow before tax	−£125,001 (−£10,417 a month)

Gross yield: 1.1%
Net yield (before mortgage): 0.8%
Return on cash in: -7.3%

Will a lender agree?

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 £534,171 or £460,493. Lenders differ.

The rent may not pass a typical lender stress test: lenders often want rent to cover interest at 7% by 125%, which caps the loan near £534,171.

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

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