Rental Property: Price the Empty Months
A rental property is a property held to produce rent rather than to live in. Its return is the rent received minus every cost of holding it, plus whatever the price does. The costs are the part beginners omit, and vacancy is the one omitted first.
How it works
A rental property is bought to let, not to live in. It is real estate held because a tenant pays to occupy it, and that rent is why the asset exists.
The rent minus everything is the only real number. Gross rent is a headline; the return is what survives every cost of holding it, plus whatever the price does.
And most beginners forget half of the everything. The omissions are predictable: vacancy, letting and management fees, maintenance, insurance, service charges, safety certification and tax on the rental income.
Empty months are a cost, not a misfortune. A property is vacant between tenants as a matter of routine, so an honest calculation prices that in from the start.
The costs left out of the sums
So is the roof, averaged across the years it lasts. A roof does not fail every year, but it fails eventually, so its cost divided by its life is an annual cost whether or not it was spent this year.
Ignoring capital items makes the early years look profitable. A boiler, windows and a rewire are dated expenses waiting their turn, and a model that omits them hands the profit back later.
One bad tenant costs more than a year of profit. Arrears, a possession process and the repairs afterwards run while the property earns nothing, and the mortgage does not pause.
And one property is a portfolio of exactly one. One undiversified, illiquid asset with a single tenant, where a local employer closing or a change in the letting rules hits all of it.
Management is a real fee whether you pay it or do it. An agent takes a share of the rent every year; doing it yourself pays the same cost in hours.
In practice
There is no order book and no daily price. Nothing here has volume or a quoted bid, so liquidity exists only when a buyer does.
The return arrives slowly and mostly as rent. Rent is the part you control and can measure; price growth is the part you cannot. A purchase justified only by appreciation is a speculation with a tenant attached.
And a rate rise changes the arithmetic overnight. A mortgage is leverage, so the rate can move the whole result — and unlike an opening gap it arrives on a date you already know.
Selling takes months, which is the real risk. There is no stop loss on a house, so risk management here is the reserve you hold, not the level you leave.
And every transaction costs far more than 2% of a bar. On this site’s shared history a round trip costs 0.0098 price units, 2% of a median bar’s range. A property costs a large multiple of that to trade, before capital gains tax.
Building an honest cash-flow model
Start from a rent you could actually achieve, not the one the listing hopes for. Everything after that is subtraction, and the order matters because it keeps the borrowing last.
Subtract an allowance for vacancy first, then management. Both are certain: the property will be empty sometimes, and someone does the letting work whether or not an invoice records it.
Then annualised maintenance and capital items, then insurance, service charges and tax. The roof, the boiler and the windows enter as their cost divided by their life, so no year looks artificially clean. It is the discipline a cash flow statement imposes on a business.
Only then the mortgage. If the remainder is negative, the purchase does not depend on the tenant at all; it depends entirely on the price rising, and that should be said out loud before the offer rather than discovered afterwards.
What a rental property is not
It is not passive income. It is a small business with one customer.
It is not a savings account. The capital is illiquid and the monthly figure can be negative.
It is not house hacking. Living in part of the building changes the arithmetic entirely.
And it is not the BRRRR method — buy, refurbish, rent, refinance, repeat — which recycles one deposit through several properties.
When it fails
In a flat market it is a job that pays a yield. With prices in a trading range the appreciation half of the case disappears, leaving management work paid for by rent.
The failure that matters is the month you never modelled. A void alongside a capital repair turns a property that looked comfortable into one funded out of savings.
A second is a purchase that only worked if prices rose. Negative cash flow is survivable when it was chosen and funded, and not when it was a rounding error.
A third is the tenant who stops paying. Recovery is slow, the costs land in one lump, and the property earns nothing throughout.
A fourth is a rate reset on a leveraged purchase. The date is known years ahead, which makes it the most forecastable risk here and the one most often ignored.
And a fifth is mistaking the absence of a price for the absence of a drawdown. On this site’s shared history 95% of bars sat below a prior peak, the longest stretch running 73 bars.
The original data
The appetite here is enormous and the supply is almost nothing. In research/broker-coverage.json,
a scan of the 24,971 videos in research/search-study-corpus.jsonl, 20 videos carry “rental property”
in the title at a median of 161,324 views across 15 channels, the largest at 5,143,930 — one of the
highest medians measured anywhere on this site. Exactly one title in 24,971 contains “landlord”, at
466,140 views, while 171 videos cover real estate at a median of 26,672.
And the fee arithmetic is the part nobody models. In research/series-measurements.json, built by
site/measure_series.py, an annual charge compounding alone over thirty years costs 1.5% of the pot
at 5 basis points, 5.8% at 20, 20.2% at 75 and 36.5% at 150. A letting agent’s share of the rent is an
order of magnitude larger than 75 basis points, taken every year, and it is routinely left out of the
sums done before buying. Model the property with a vacancy allowance and an annualised roof before you
make an offer, not after.
Related
Real estate is the wider asset class this sits inside, including the parts that never produce rent. Passive income is the claim most often made about letting, and the one this page argues with. And a mortgage is where most of the result is decided, because the borrowing sets the size of the bet.
The number that sold me on my first one was the rent, and the rent was the only number I had. What actually landed in the account was smaller every month, and it was smaller for reasons that were all perfectly predictable before I bought. Nothing went wrong, exactly. I had written down the top line and called it the answer.
— Michael Whitman
This page is educational, not financial advice. Test every idea on your own charts before risking money.