Which door makes you money?
Most landlords know the portfolio makes money overall. Almost none can say which property does — and which one quietly loses it. The average hides the loser. Here's how to find it, and why a healthy yield can still mean a door that barely breaks even.
Plain English · UK landlords · per-property, not per-portfolio.
Portfolio looks fine. One door is bleeding.
The portfolio average hides the loser
Add every property together and you get one comforting number: the portfolio makes money. But that total is an average, and an average is exactly where a loss-making door goes to hide. The strong properties quietly subsidise the weak one — and you keep paying for it because you can't see it.
The only cure is to stop looking at the lump and look at each door on its own. Work out net profit per property, line the results up, and the property costing you money has nowhere left to hide.
One number vs four
-
Portfolio view"+£525 a month across four doors." Looks healthy. Tells you nothing about where it comes from.
-
Per-door viewThree doors carry the portfolio; one loses £60 a month. Now you know exactly what to deal with.
Same rent. Same costs. Completely different decisions.
Yield isn't profit
"Good yield" is the phrase that gets a property bought — and the one that hides whether it actually makes money. Yield is a headline percentage. Profit is what's left in your account.
A percentage on paper
Usually annual rent as a share of the property's value. Useful for comparing at a glance — but it ignores most of your costs and the mortgage.
What's actually left
Rent received, minus every running cost, minus the mortgage. The number that tells you whether the door earns its keep.
Where doors get lost
A strong yield can sit on top of a door that barely breaks even once the real costs land. Profit is the honest test.
The quiet ways a property starts losing
A door rarely announces that it's stopped making money. It slips under, one cost at a time, while the rent on paper looks unchanged. These are the usual suspects.
A remortgage onto a higher rate
The single biggest swing — a fixed period ending can turn a comfortable door tight overnight.
Empty weeks between tenants
Rent stops but the mortgage and standing costs don't. A couple of voids a year quietly eats the profit.
Creeping maintenance bills
An older property with a run of repairs can cost more to keep let than it returns — spread out, it's easy to miss.
Service-charge and ground-rent hikes
On leasehold flats these can rise faster than the rent, thinning the margin without you touching a thing.
Rank every door like for like
Finding the winner and the loser is the same job done for every property: net profit after the mortgage, on the same basis, side by side. Do that and the ranking answers the question for you — no hunch required.
How to work out net profit per property →Every door, ranked — without the spreadsheet
You could rebuild this ranking by hand every month. Or you can let Monkey Riot read your rent statements and invoices, work out net profit per door, and turn each property into one score — the Property Efficiency Score — so the winner and the loser are obvious.
Doors in order, best to worst
See every property side by side on the same net-profit basis — the loser can't hide in the average.
Feeds itself from Gmail
Connect Gmail read-only and rent and invoices flow into the right property, so the ranking stays honest.
The Property Efficiency Score
Net profit after the mortgage, distilled into a single figure per door you can act on at a glance.
Catch a door before year-end
A property slipping into the red shows up as it happens — not in the accounts months later.
Imports your file as-is
Bring the spreadsheet you already keep — messy is fine — and your history comes with you.
Refinance, fix or sell
With the ranking clear, the next move on your weakest door stops being a guess.
Which-door questions, answered
How do I find out which of my properties is losing money? +
Work out net profit for each property on its own — rent received, minus running costs, minus the mortgage — and put the results side by side. The moment you stop looking at the portfolio as one lump, the property running at a loss stops hiding behind the ones that do well. Monkey Riot does this ranking automatically from your rent statements and invoices.
What's the difference between rental yield and net profit? +
Yield is a headline percentage — usually annual rent as a share of the property's value — and it ignores most of your costs. Net profit is what's actually left after running costs and the mortgage. A property can show a healthy yield and still make little or no real profit, which is why yield alone can't tell you which door makes money.
Can a property look profitable but actually lose money? +
Yes. A remortgage onto a higher rate, a run of voids, creeping repair bills or a service-charge rise can quietly turn a door negative while the headline rent looks unchanged. Because the loss is spread across the year and hidden in a portfolio total, many landlords don't see it until the year-end accounts — by which point it has cost real money.
Should I sell a rental property that doesn't make money? +
Not necessarily — a door that loses money on cash flow today might still be worth keeping for capital growth, or be fixable with a remortgage or a rent review. The point of knowing net profit per property is that the decision to refinance, fix or sell becomes a clear-eyed choice rather than a guess. This is general information, not financial advice; speak to a qualified adviser about your situation.
How does the Property Efficiency Score rank my properties? +
Monkey Riot reads your rent statements and invoices, works out net profit per property after the mortgage, and turns each door into a single Property Efficiency Score. That lets you rank every property on the same basis and see at a glance which one makes you money and which one needs attention next.
Related guides
How to work out net profit per property
The one-door calculation, and the Section 24 tax catch that trips landlords up.
The spreadsheet alternative for landlords
Why Excel breaks at 4–25 properties, and how to switch without re-typing a thing.
See the Property Efficiency Score
One number per door — net profit after the mortgage, worked out for you.
This page is general information for UK landlords, not financial or tax advice. Whether to keep, refinance or sell a property depends on your circumstances, and tax treatment can change. Always check the current guidance on GOV.UK or speak to a qualified accountant or adviser before making decisions.