Rented normally, it costs you £1,243 a month. That is £14,913 a year, every year you hold it.

Will it pay?Calculator

The mortgage alone costs more than the whole rent — you top up £1,243 a month

It is £1,243 a month short. Borrowing £229,426 less would close that shortfall — which is £229,426 more cash at the start, on top of the deposit.

£4,773 mortgage

£4,653 rent in£1,243 short

◧ market rent £4,653 · 1 comp2 empty weeks a year assumed

What if I change my assumptions?The dials

At the asking price, 25% deposit, 6.50% charged

Change any of these 16 and every card on this page changes with it. The 6.50% is the 5.75% quoted plus a company premium.

◧ worked out from local rents

What will it cost me to buy?Breakdown

£436,075 + refurb costs

And about £74,563 more over five years, because it loses £1,243 every month you hold it — before any repair. That already assumes the rent never falls.

£436,075 to buy it

deposit · stamp duty · solicitor · fees~£44,951, unseen

□ works not inspected

What would have to be true?The working

£305,000 off and it stops losing money

At the asking price you feed it £1,243 a month. At £869,087 the rent covers everything — leaving stamp duty of £76,909 at that price.

offer £869,087

asked £1,175,000

◧ worked back from the rent■ stamp duty re-bandedrounded down to £5,000 — the rent it works back from is an estimate

Is the price right?The deeds

Last sold for £963,000 in 2020

Nothing nearby is comparable, but asking is 22% more than the £963,000 paid for it in 2020.

□ this address’s own deeds, no comparable saleHM Land Registry Price Paid Data

What will the rent borrow?Lender test

The rent carries £493,687 of the £881,250 loan

That £387,563 is yours to find on top of the deposit. Tested at 125% instead of 145% — a company or a basic-rate taxpayer usually is — the gap is £308,573. Lenders test the rent at 7.5% and need it to cover 145% of the payment.

£7,986 needed

more than the £4,474 rent

stressed at 7.5%, 145% cover

◧ rent after empty weeks £4,474PRA-style test

Who has to say yes?Council record

Lewisham council decides

Named from the postcode, with no decision record under it. Check Lewisham council's pre-application advice before you commit to a room-let plan.

■ Article 4 — planning permission required◧ authority from the postcode□ no decision recordfrom the Article 4 map we hold

How big is it, really?The plan

One figure, and nothing checking it 2,160 sq ft

Only the agent’s figure exists for this house. Open for what that means.

□ area unchecked — agent’s own

Is it a good location?Open the map

London, SE23 2QR

2 of 5 schools in this postcode area rated Good or Outstanding and flood risk checking… — open for the map, the schools and the rest.

Article 4Planning permission required to let by the room

■ postcode area, not this address

What could kill thisThe checks

You would need a licence from the council first

Letting without the council’s licence is an offence, and the fee is in no figure here.

3 problems found · 2 came back clear · 3 we could not check · 1 does not apply to this property

■ from council licensing registerlisting last seen 15 Sep 2026

Which strategy wins?The ways to run it

Every way loses money — Standard rental loses least, at £1,243 a month

Let it to the council: £15,120 a year less, but they keep paying when it is empty.

Standard rental−£1,243 · £481,026 in

Guaranteed council rent−£2,503 · £481,026 in

Rent by the room−£2,846 · £481,026 in

Housing-benefit rent−£3,040 · £481,026 in

Each row: money kept a month, then the cash it ties up. Not compared: Do it up, then remortgage (pays back at the remortgage) · Short-stay let (no local short-let data) · Buy, improve & sell (pays out on sale)

◧ 4 ways, one measureranked on money kept each month, at the asking price

What would you walk away with?The five-year sums

−£146,733 after five years on the cash you put in, before tax on the sale

Less than the same cash would have made in a savings account, after tax on the interest. The savings account’s capital is not at risk; the property’s is. A fall of about 25% in the price would leave nothing from a sale after selling costs, and you would still owe the lender any shortfall. That is the £481,026 you put in. The 5-year fix runs past this 5-year hold, so the rate reset comes after it.

◧ 2.0%/yr growth assumed