How to Size a Reserve Fund for Your Short-Term Rental

A reserve fund is the clearest line between a short-term rental that is a business and one that is a hobby with a booking calendar. The business has money set aside for the roof before the roof fails. The hobby has a very good June and an owner who is surprised in February.

Short-term rental is a business, not passive income. It is passive for the owner, because somebody else is doing the work — but the money still behaves like a business's money. That means two reserves, not one, and it means building both from the house in front of you rather than from a percentage you read somewhere.

Two reserves, not one

Most owners who tell us they have a reserve have one pile of cash doing two incompatible jobs. The two jobs fail at different times for different reasons, and a single pile hides the moment one of them runs dry.

Reserve	What it pays for	Behavior
Capital reserve	Replacing things that wear out — roof, HVAC, water heater, appliances, flooring, furniture, pool equipment	Predictable in total, unpredictable in timing. Nothing happens for three years, then two things happen in one month.
Seasonal reserve	The months when payouts do not cover fixed costs	Predictable in timing, variable in depth. You know which months. You do not know how deep until you book them.

Fund them separately. Track them separately. A capital reserve that quietly covered a slow August is not a capital reserve anymore, and you will not notice until the compressor goes.

Why percentage-of-revenue rules do not survive a short-term rental

The reserve rules of thumb that circulate among owners are nearly all inherited from long-term rentals, and they are all percentages of rent. That works when rent is the same number twelve times a year. It does not work here. Short-term rental revenue swings hard between peak and trough, so a fixed percentage over-reserves in your best months and under-reserves in exactly the months you need the cushion.

There is a second problem. A short-term rental takes more wear than a long-term tenancy at the same address — more turnovers, more people through the door, more laundry cycles, more hours on the HVAC because guests do not run the thermostat like someone paying the bill. A percentage borrowed from the long-term world is being applied to a house that is consuming itself faster.

So build the number from the bottom up. It takes an afternoon, once a year.

Build the capital reserve from your own replacement schedule

List every component in the home that will need replacing and that you would have to pay for in one payment. For each one you need two facts: what it would cost to replace today, and how many years you have left before you expect to.

Component	Where your numbers come from
Roof	Replacement date in your closing documents or inspection report; a current quote from a local roofer
HVAC	Install date on the unit's data plate; a replacement quote from whoever services it
Water heater	Install date on the tank label; a quote from your plumber
Appliances	Your purchase receipts, or the manufacture date encoded in the serial number; current retail plus installation
Flooring and interior paint	Your own walkthrough, honestly done, plus a painter's or flooring installer's quote
Mattresses, sofas, case goods	The date you bought them. These turn over far faster in a rental than in a home you live in.
Pool and spa equipment	Your service company — pumps and heaters are the line most Florida owners leave off the list entirely
Exterior paint, decking, screens	A local contractor. Coastal exposure shortens every one of these.

Then the arithmetic, one line at a time:

Replacement cost quoted today ÷ years remaining = annual accrual.

Add the annual accruals. Divide by twelve. That is your monthly capital reserve contribution, and it is a real number about your actual house rather than a percentage about a hypothetical one.

Two rules keep this honest. Quote what replacement costs today, not what you paid in 2019 — you are funding a future purchase at future prices, and quoting the old number guarantees a shortfall. And re-run the whole schedule once a year. Every year that passes moves every component one year closer, which means the required monthly contribution goes up even when nothing breaks.

Build the seasonal reserve from your own payout history

Pull twelve to twenty-four months of payout statements — from the platforms directly, or from your owner statements if you are managed. Then:

1. List the costs that arrive every month whether or not anyone is in the house: mortgage, utilities, lawn and pool service, internet, pest, management fee.
2. For each month, subtract those fixed costs from that month's actual payout.
3. Write down every month that comes out negative, and by how much.
4. Add the negative months together. That total is your seasonal reserve.

The timing matters as much as the amount. The seasonal reserve has to be fully funded before the slow stretch begins, which means it is funded out of peak-season cash, which means peak season is not the month to take a distribution equal to the whole payout. If you do not yet have twelve months of history, set a target from the fixed costs alone and reserve a fixed share of every peak-month payout until you hit it.

Slow season is not the same month everywhere

This is where generic reserve advice does the most damage. We operate in two markets with opposite calendars.

In the Triangle — Raleigh, Durham, Chapel Hill — demand tracks the university and medical calendars: graduation weekends, move-in, parents' weekends, basketball, and steady midweek business and relocation travel. The soft stretches sit in the gaps between those anchors.

In Southeast Florida — Miami, Hollywood, Dania Beach, Fort Lauderdale, Pompano Beach, Deerfield Beach, Delray Beach, Lantana — the pattern inverts. Winter is the season. Late summer is the trough, and it is a longer trough than most first-year owners plan for.

An owner with a home in each market cannot run one reserve schedule across both. The funding months are different, the trough depth is different, and the capital list is different — a Pompano Beach pool home and a Durham three-bedroom do not wear out the same parts.

This is the structural problem with national management. A company operating in dozens of markets runs one playbook, because one playbook is the only thing that scales across dozens of markets. You get a single reserve percentage and a single seasonal calendar, neither of which describes your house. It is not that they are careless. It is that doing this well requires knowing which weekend in your market fills and which one does not, and that knowledge does not travel.

Three things owners get wrong

Treating the reserve as profit that has not been spent yet. It is not yours. It is already committed to a water heater you have not met. Owners who draw their reserve down in a strong year are not ahead; they are borrowing from a bill with a due date they do not control.

Sizing it once, at purchase, and never again. The inspection report ages. Every component moves a year closer each year, so a reserve contribution set at closing is already too low by the second season.

Keeping it in the operating account. Money that is visible gets spent. A separate account with a separate name is the entire discipline, and it is the cheapest operational change an owner can make.

What good looks like

An owner with a working reserve can answer three questions without opening a spreadsheet: what the monthly capital contribution is, what the seasonal reserve target is, and which month it has to be fully funded by. If those three numbers are not at hand, the reserve is a hope rather than a plan — and the house will eventually put that to the test.

If you own in the Triangle or in Southeast Florida and you want a grounded view of what your home should actually produce across a full year — peak and trough both — we will put together a free revenue estimate for your property. It is the number the whole reserve schedule is built on top of, and it is worth getting right before you size anything else.