Short-term and holiday lets can look attractive on paper. A strong nightly rate multiplied by a busy summer often produces a headline yield that beats long-term rental at first glance. The difficulty is that the numbers only hold up when you model the full year, not the best fortnight in July.
Buyers evaluating a mountain apartment, a coastal villa, or a city flat need a cashflow picture that reflects seasonality, operating costs, and tax in roughly the right order. This article outlines what belongs in that picture and where optimistic forecasts usually go wrong.
Why a single annual figure is rarely enough
Many back-of-envelope calculations assume one average nightly price and one occupancy rate for the whole year. That works for a quick sanity check, but it smooths away the detail that drives real returns.
Demand, pricing power, and running costs rarely move in a straight line. Shoulder months behave differently from peak season. Fixed charges such as local property tax and community fees still apply when guests are scarce. A model that treats every month the same will usually overstate net income unless you deliberately use conservative assumptions.
A useful mindset
Think in monthly cashflow, not one annual percentage. If the quiet months still leave you with acceptable coverage of mortgage and fixed costs, the peak season is upside rather than a rescue plan.
Gross income: rates, nights, and occupancy
Gross short-term rental income starts with how many nights you can realistically sell and at what price. Nightly rates often flex with season, local events, and competition from similar listings. Occupancy is the other half of the equation. A premium rate with weak occupancy can deliver less than a moderate rate with steady bookings.
When researching a market, look beyond advertised averages. Compare listings similar to yours in size, location, and amenities. Ask how owners handle minimum stays, cleaning turnaround, and gaps between bookings. Those constraints affect usable nights even when demand is strong.
You do not need perfect forecasts at the offer stage. You do need a range: a cautious base case, a plausible mid case, and a stretch case that still feels achievable rather than heroic.
Operating costs guests create
Short-term stays tend to consume more utilities and services per night than a long-term tenant. Electricity, water, heating, and internet often rise with turnover and guest use. Cleaning between stays is another line item that long-term models sometimes ignore entirely.
Platform or booking fees also belong here. Whether you use a major portal or a mix of channels, a share of gross income typically leaves the table before you see net cash. Management companies, if you use one, usually take a percentage of revenue, a fixed fee, or both, and may charge extras for guest communication, maintenance call-outs, or linen.
Treat these costs as variable with activity where possible. A month with fewer guests should not carry the same utility and cleaning burden as a fully booked August.
Fixed costs that do not pause in winter
Some property expenses are largely independent of how many guests arrive. Local property tax, building insurance, and community charges typically continue through low season. In many setups they are paid once a year or quarterly rather than spread evenly across months, which can create lumpy cashflow even when average annual figures look fine.
Maintenance and small repairs also accumulate over time. Short-term use can accelerate wear on kitchens, bathrooms, and furnishings. A prudent forecast reserves something for upkeep even in years when nothing major breaks.
Tax and reporting: keep the treatment consistent
Rental income is taxable in most jurisdictions, and short-term letting is no exception. The rate and filing rules depend on residency, how the property is owned, and whether you rent as an individual or through a structure. Spain, Andorra, and other markets each have their own thresholds, deductions, and local obligations.
At modelling stage the important point is consistency. Decide whether you are comparing gross income to a flat tax on gross, or net income after allowable expenses. Mixing the two across scenarios makes comparisons misleading. If certain operating costs can reduce taxable income in your situation, reflect that in the same scenario rather than applying it selectively to improve one outcome.
Licensing, registration, and tourist taxes add another layer that varies by municipality and region. They may not dominate the spreadsheet, but they can affect legality and net margin. Confirm local rules before you rely on STR income in your purchase case.
Short-term vs long-term: compare like with like
Long-term rental models are simpler. A monthly contract, fewer turnovers, and lower utility volatility produce a steadier line on the chart. Short-term can win on gross yield in the right location, but it trades that for operational intensity and seasonality risk.
When deciding between strategies, compare net cashflow after all costs and tax, not headline nightly rates. Factor in your own time if you plan to self-manage. Factor in vacancy and regulation risk if you depend on peak weeks to cover the year.
Questions worth stress-testing
- What happens if occupancy in the shoulder season is 30% lower than hoped?
- What if the platform fee or management rate rises?
- Can fixed costs still be covered if you lose four to six peak weeks?
- How does the outcome change if you switch to long-term letting?
Building a forecast you can defend
A defensible short-term rental forecast usually combines seasonal revenue assumptions with a clear list of variable and fixed costs, then applies tax treatment in a way that matches how you will actually report income. You want enough detail to see where margin disappears, without pretending precision you do not have.
Start from local evidence, stress-test the quiet months, and separate purchase economics from operating economics. The purchase case should still work if STR income is merely good rather than exceptional.
Explore purchase costs and holiday rental cashflow in the property calculator. Choose your country and set purchase intent to short-term rental to work through seasonal income and running costs alongside mortgage and return projections.