Marcos lives all year round in a 100 m² flat and lets a 15 m² room for 120 nights. The guest also uses the bathroom, the kitchen and the hallway. Marcos cannot declare as if he were letting the whole home, nor can he limit every cost to the 15 % that the room represents. He needs to mark out the exclusive and the shared areas, apportion the time and keep a record of the method, because that use can also matter when he sells his main home.
You declare the rental even though you still live there
Letting only one room does not remove the obligation to declare the income. The difference lies in drawing the boundary: part of the home remains for your personal use and part is given over to the guest on certain days. Shared costs have to be split using a reasonable criterion of floor area and time.
The licence or tourism notice depends on regional and municipal rules. Some regulations allow letting by the room; others treat a tourist home as a letting of the whole property, or require a different type of registration. Before you advertise it, confirm that this way of operating is allowed.
Two dimensions of the split
| Dimension | Question |
|---|---|
| Floor area | Which square metres are exclusive to the guest and which are shared? |
| Time | On how many days was that part actually let? |
A 15 m² room in a 100 m² home does not automatically mean deducting 15 % of everything. The guest may use the bathroom, the kitchen and the hallway, while other areas stay reserved. Define a method that reflects the use and keep to it.
You can send the floor plan, the listing and the calendar through the holiday let form. The wording of the listing is relevant evidence: if it promises access to the living room, the terrace and the kitchen, the split cannot later ignore those areas without an explanation.
The guest's room, shared areas and private spaces
It helps to draw three categories. The guest's room is exclusive during the stay. The kitchen, bathroom or hallway may be shared. The owner's bedroom and a closed study remain private.
You do not simply add all the common square metres as though they belonged to the guest alone. A reasonable fraction can be assigned according to how many people use them, what they are used for and the conditions set out in the listing. What matters is applying the same criterion to comparable income and not changing it at the end of the year to maximise the expense.
| Area | Floor area | Treatment in the example |
|---|---|---|
| Guest's room | 15 m² | Exclusive use during the booking |
| Kitchen, bathroom and hallway | 20 m² | A share is assigned for shared use |
| Private areas | 65 m² | Not linked to the rental |
If two owners and one guest live in the home, the criterion for the shared areas may differ from the case of a single occupant. No universal percentage can replace the facts.
A worked example
Marcos's home measures 100 m². The exclusive room takes up 15 m², and 10 m² of common areas are assigned to shared use. The part linked to the rental would be 25 %. If the room is let for 120 days and an annual shared cost comes to 1,200 €, the calculation runs like this:
- Floor area linked to the rental: 15 + 10 = 25 m².
- Share by area: 25 / 100 = 25 %.
- Share by time: 120 / 365.
- Reference cost: 1,200 × 25 % × 120 / 365 = 98.63 €.
This is an example of a method, not a universal rule. Electricity used during a stay may call for a different criterion. A platform commission relates directly to the booking and does not need the same split by square metres.
Costs and evidence
Keep a floor plan or the cadastral floor area, photographs of the areas advertised, the booking calendar and the bills. Separate:
- Direct costs of the room and of each stay.
- Shared costs of the whole home.
- Purely personal costs.
- Furniture or equipment that has to be depreciated.
The guide to deductible expenses explains the IBI (the annual municipal property tax), community fees, utilities and depreciation. Do not count costs twice if someone else shares ownership.
A different criterion for each family of costs
Direct costs do not need the same double apportionment. The commission a platform charges for a booking is tied to that income. Replacing a lock that serves only the guest's room may have a direct link. The IBI, community fees and insurance, on the other hand, relate to the whole property and have to be split.
Utilities also raise the question of consumption. The guest may push up electricity and water during the stay, but an annual bill includes Marcos's own private use. If there is a separate meter, keep its readings; if not, apply a reasonable and stable method, without mistaking it for a fixed legal rule.
Durable furniture and equipment may have to be depreciated. Buying a bed for 900 € for the room does not always mean deducting the full 900 € on the day you pay. Its nature, the date it was brought into use and the period linked to earning the income all have to be looked at.
| Cost | Possible criterion |
|---|---|
| Commission on a booking | Direct link with the income |
| IBI and community fees | Floor area and time |
| Electricity and water | Proven use or a reasonable split |
| Bed and furniture | Use in the rental and depreciation |
| Repair to a private area | Not linked to the rental |
Remaining on the padrón, the municipal register of residents, helps to describe the use, but on its own it does not show which square metres, days and services were given over to the rental.
The effect when you sell your main home
The exemption for reinvesting in a new main home requires working out which part keeps that character. If an area has been given over, in a separable way, to an activity, or used for the rental, the exemption on the gain may not reach the whole home. The proportion, the time that has passed and the actual use have to be reviewed at the date of the sale.
There is no safe rule saying that letting "just one room" never affects the exemption. Keep the calendar and the physical boundary from the first year; rebuilding them when you sell is far harder.
An example on sale
If the home produces a gain of 80,000 €, you should not assume that all of it is covered by the exemption just because Marcos stayed on the padrón. First you identify the part of the home, and the periods, that kept the character of main home, and the area that was given over to the rental. Then the reinvestment rules and the deadlines in force are applied.
We do not give a closed figure, because it is not enough to multiply 80,000 € by the 25 % used for the costs. The actual boundary, whether the letting stopped before the sale and whether the main-home requirements were met over time can all play a part. The annual record sheet lets that analysis be done on facts.
VAT and services
Letting a room without services typical of the hotel industry can follow the general exemption for accommodation. If you offer cleaning during the stay, breakfast, a continuous reception or other services, look at the whole package. See which services count as hotel services.
You also have to check the rules on living together, occupancy, safety and traveller reporting. Sharing your home does not remove those obligations.
If you are a tenant and sublet the room
Before any tax calculation, check that your contract and the applicable rules allow subletting or letting to tourists. Being allowed to live in the flat is not the same as being allowed to exploit it. Doing so without permission can have civil or administrative consequences even if you declare the income.
For tax purposes, the legal title and the payments change the structure of costs: there is no IBI of your own and no depreciation of the property, but part of the rent you pay may be linked to earning the income, if the requirements are met. Keep the contract, the permission and the receipts.
If the room stops being let
Fix the date of the last guest and keep proof that the listing was taken down. From that moment the income disappears, but you cannot go on deducting the percentage of costs you had assigned to the rental. If you take the room back for your own use, it becomes part of your private use again. When you switch several times within the year, the calendar has to show each period, not a rough average taken when the return is closed.
A simple record
Create a sheet for the home with total square metres, the room, the common areas, the percentage used and the date of each stay. Add a column for each cost and its criterion: direct, by area, by time or mixed. You must be able to explain the method without changing it at the end of the year to get a more favourable result.
The general picture is in tax on tourist rentals. If the property belongs to several people, see how it is split between co-owners. Keep a yearly copy of the floor plan, the listing and the calendar, even if the platform closes your account or changes its history.