Subletting a home: what to check if the tenant wants to rent out a room

Subletting a room: why you should not take it for granted

If your tenant asks to rent out a room in the property, you should not treat it as a mere favour or as something automatic. In a residential tenancy, partial subletting is only possible if the landlord gives written consent. The LAU clearly distinguishes between assigning the contract and partially subletting, and both arrangements require different precautions. Under article 8, “the rented dwelling may only be partially sublet with the prior written consent of the landlord” and “the contract may not be assigned by the tenant without the written consent of the landlord” BOE-A-1994-26003.

This matters because authorising one room does not mean authorising any other transfer of use. Nor does it mean that the tenant can increase the number of occupants on their own initiative, change the property’s use or turn the arrangement into a disguised assignment. The key is to check precisely what is being authorised, to whom and on what terms.

What you should check before giving your written consent

Before signing or replying in writing, check these points:

1. **That this is genuinely a partial sublet.**

The LAU only allows the partial subletting of the dwelling. If the tenant intends to hand over the use of the whole flat, we would no longer be dealing with a room, but with a legally different and therefore much more sensitive situation.

2. **That the request is made in writing.**

A conversation, an informal message or a phone call is not enough. If you authorise it, make sure the authorisation and its exact scope are recorded in writing.

3. **That the specific room or area is identified.**

It is advisable for the authorisation to describe which space is being sublet and which spaces remain linked to the main tenant’s use. This helps avoid disputes over the kitchen, bathroom, living room, storage room or communal areas.

4. **That it is clear who remains responsible to you.**

Even if the tenant and the subtenant have their own agreement, the tenant remains your main point of contact. It is therefore wise to state in writing that there is no replacement of the tenant and no assignment of the contract.

5. **That the residential purpose is respected.**

Article 8 states that the subletting is governed by the rules on leasing when the sublet part is used by the subtenant for the purpose referred to in article 2.1, that is, to satisfy a housing need. If that condition is not met, the parties’ agreement will apply.

How to draft the authorisation to avoid misunderstandings

The best practice is to issue a short but complete authorisation. It does not need to be complicated, but it should set out the essential points. It may include:

1. **The details of the original contract** and the parties.

2. **Identification of the room** or area authorised.

3. **Express consent to sublet only on a partial basis**.

4. **A prohibition on assigning the contract** and a clarification that consent does not imply it.

5. **An obligation for the main tenant to remain liable** under the contract.

6. **A requirement for the subtenant to use the room as a home** if that is the intended purpose.

This approach reduces the risk of later disputes about whether you authorised a specific room or, unintentionally, permitted a wider occupation.

Common mistakes worth avoiding

There are several frequent errors that cause problems later on:

- **Giving verbal approval.** It is then difficult to prove exactly what was authorised.

- **Thinking that a room does not need permission.** It does: article 8 requires written consent.

- **Agreeing to a sublet without setting limits on use.** If you do not specify, a different use from the one intended may arise.

- **Confusing subletting with assignment.** In an assignment, the occupant takes the tenant’s place; in a partial sublet, that does not happen.

- **Not considering the impact on cohabitation.** Even if the LAU allows it with consent, the arrival of another person may alter the normal use of the property, running costs and relations with neighbours.

A useful practical test is to ask yourself: would the written authorisation make it clear, without room for doubt, that only one room is permitted and not a transfer of the contract? If the answer is no, it is worth redrafting it.

Practical steps if your tenant raises the issue

1. Ask for the request in writing and for an explanation of the use they intend to give the room.

2. Review the original tenancy agreement to check whether there are any clauses on occupants, cohabitants or subletting.

3. Prepare an express authorisation if you agree, always in writing.

4. Define the partial scope: the specific room, shared spaces and any prohibitions.

5. Make clear that there is no automatic assignment of the contract or release of the main tenant.

6. Keep copies of all the documentation.

If you would prefer to consider the case in detail before replying, you can request guidance about your property at /contacto or ask for an estimate at /valoracion-vivienda-madrid, bearing in mind that the online estimate is indicative, not an official valuation, and includes a range and PDF report, with an optional visit.

When it is worth seeking individual advice

General guidance is useful for understanding the basic rule, but it does not replace an analysis of the specific contract. It is sensible to review the case individually if:

- the property is shared by several tenants;

- the contract includes special conditions on occupants;

- the subletting is being proposed for a room within a larger space, rather than a closed room;

- there is already a dispute between landlord and tenant;

- you want to limit duration, occupancy or the use of common areas.

In these situations, a poorly drafted authorisation can end up operating as an extension of use that you never intended to accept. So, if you do allow it, always set out the partial scope in writing and remember that consent to sublet a room is not an automatic assignment of the contract.