Why this is not a detail
Nights let decide three things simultaneously: what proportion of your costs is deductible, how many days are left over as "at your disposal" for the deemed-income charge, and — if you ever charge VAT — what share of your input VAT you may recover. Get the count wrong and you have shifted money in three places without noticing.
You count nights, not calendar days
A stay from 28 March to 2 April is five nights: the 28th, 29th, 30th, 31st and the 1st. The departure day does not count, because the guest is no longer there that night. It sounds obvious written down, and it is the first thing that goes wrong in a spreadsheet built at the end of the year.
That same stay puts four nights in the first quarter and one in the second. It does not go wholly to the period it started in, nor to the period the money arrived: each night counts where it falls. With a handful of bookings this is pedantry. With three hundred, counting by eye introduces a systematic error that always leans the same way.
The apportionment formula
Cost for the period × (nights let ÷ days in the period). With 120 nights in a year, an electricity bill of 600 € contributes 197.26 € of deductible cost, and 402.74 € that simply is not deductible. The denominator is the days in the period, which is 365 for a full year and something smaller if you bought or sold the property partway through.
What gets apportioned and what does not
| Apportioned by nights | Deductible in full |
|---|---|
| IBI, the annual local property tax charged by the town hall, and the refuse charge | Cleaning between guests |
| Service charge paid to the comunidad de propietarios, the owners' association of the building | Booking platform commission |
| Electricity, water, gas, internet | Laundry of linen used by bookings |
| Buildings and contents insurance | A repair caused by a particular guest |
| Depreciation of the building and of the furniture | Guest welcome packs and consumables |
The rule behind the table is one line: if the cost would exist with the flat standing empty, it is apportioned. If it only exists because a guest came, it goes in whole. Apportioning the cleaning and the commission is giving away deduction. Deducting the electricity or the property tax in full is exposing yourself at the first review.
Two words a foreign owner may not know
IBI is the annual tax levied by the town hall on the rateable value of the property. The bill is also where you find the valor catastral, the rateable value set by the land registry office, which matters because the deemed-income charge is calculated on it. The comunidad de propietarios is the owners' association every block of flats has by law: it charges a monthly or quarterly service charge for lifts, cleaning, insurance of common parts and so on, and occasionally votes a derrama, a one-off levy for works. Ordinary service charge is a running cost; a levy for genuine improvement works is capitalised and recovered through depreciation instead.
The four kinds of day in a year
| Kind of day | Counts as let? | Produces deemed income? |
|---|---|---|
| Let for consideration | Yes | No |
| Empty but advertised | No | Yes |
| Used by you or your family | No | Yes |
| Closed for works | Arguable, and it depends on whether the works were needed to keep letting it | Usually yes |
The last row is the one that gets argued. Essential maintenance carried out in the low season defends well. A full eight-month refurbishment defends badly, because for most of the year the property was not available to anybody.
There is a long-running argument that a property advertised and available all year should be treated as wholly used in the business. The settled administrative view is the opposite: real occupancy counts, not commercial availability. Until that changes, apportioning by nights actually let is the prudent position, and it is the one we apply. We would rather tell you that now than defend the other one for you later.
How the count is documented
- Platform settlement statements, which already list each booking with its arrival and departure dates. This is the backbone of the record.
- Contracts or receipts for direct bookings, with check-in and check-out written on them.
- An annual register per property, totalling nights by quarter and reconciling to the income declared.
That register is not housekeeping for its own sake. It is what turns a deduction into a defensible deduction. A review wants to see three things chained together: the invoice for the cost, the booking record the night count comes from, and the calculation joining them. When the middle link is missing, the deduction falls in its entirety, not merely in the part being questioned.
A worked year
A flat let 146 nights, with annual costs of: property tax 320 €, service charge 660 €, utilities 980 €, insurance 210 €, cleaning between guests 1,840 € and platform commission 2,100 €.
- Letting proportion: 146 ÷ 365 = 40 %.
- Apportionable costs: 320 + 660 + 980 + 210 = 2,170 € → deductible 868 €.
- Costs deductible in full: 1,840 + 2,100 = 3,940 €.
- Total deductible: 4,808 € out of 6,110 € spent.
Apportion everything, including the cleaning and the commission, and you would have deducted 2,444 € instead — paying tax on 2,364 € that was never profit.
More than one property, and part-years
Each property carries its own count. Costs belonging to one property go to that property; costs shared across several — an insurance policy covering two flats, your own website, professional fees — are split between properties on a reasonable basis first and then apportioned by each one's nights. Doing that double split by hand is tedious; doing it from a proper booking register is trivial.
If you bought in May, the denominator is not 365: it is the days you owned the property. The same applies on a sale. And if a property only entered the letting business partway through the year, costs incurred before that date are not costs of the business, even though they were paid.
Where this shows up on your return
For a non-resident owner the apportioned figure feeds form 210 twice: once in the rental return, and once in reverse, because the days that were not let produce the deemed-income charge described in deemed rental income. For a resident owner it feeds the property income section of the annual return. Either way, the night count is the hinge. You can run the numbers in the apportionment calculator, and if you want the full list of what is deductible in the first place, see deductible costs on a holiday let.
Questions we get asked about your holiday let
What about the nights I use the flat myself?
They are not business days. They reduce the deductible proportion and they add to the days at your disposal for the deemed-income charge. It is the correction most often missing from a count done by eye, and it is the first one checked when the property sits somewhere the owner is likely to holiday.
Do I count days it was advertised but empty?
No. Real occupancy counts, not commercial availability.
My platform reports gross, before commission. Does that matter?
For the night count, no. For the income figure, very much so: the gross amount is your income and the commission is a cost, not a reduction of turnover. Netting them off understates both sides and makes the figures impossible to reconcile against what the platform reports about you.