Sale of co-ownership share: how to proceed if you only own part of the flat

What it means to sell a co-ownership share when you only own part

When a property belongs to several people in co-ownership, each of them holds a share or interest in the property. In practice, that means you do not own the whole flat on your own, but rather an undivided share. The main consequence is clear: you cannot unilaterally transfer the entire property if the other co-owners are not involved in the transaction.

The Civil Code distinguishes between ordinary co-ownership and the division of common property. In addition, in horizontal property, common parts cannot be divided and can only be transferred together with the private part to which they are linked. Article 396 of the Civil Code sums it up as follows: “The parts held in co-ownership are in no case capable of division and may only be sold, charged or attached together with the specific private part to which they are an inseparable annex” Civil Code, art. 396.

Therefore, if your aim is to sell “the whole flat”, you must first know whether you only hold a share or whether, in fact, you are a co-owner of a private element with its inseparable annexes. That difference changes the scope for action.

What a co-owner can do on their own

If you own an undivided share of the property, you can normally sell your share without the other co-owners having to sell theirs. What you cannot do on your own is sell 100 % of the property as if you were the sole owner.

In practice, selling only part can be more complex because the buyer enters into a community with other owners. That is why it is sensible to prepare the transaction properly and make very clear exactly what is being transferred.

### Useful steps to act in an orderly way

1. **Check the title deed and exact share**

Review the deed or document that grants you the co-ownership to identify the percentage that belongs to you and whether there are any annexes or restrictions.

2. **Check whether it is an ordinary co-ownership property or a flat subject to horizontal property**

In the latter case, common elements are not separated from the flat. Article 401 of the Civil Code adds that, if the building allows it, division may be made by assigning independent flats or units, with their attached common elements, but this will not always be possible or automatic.

3. **Consider selling your share or negotiating a joint exit**

If the other co-owners do not want to sell, the individual transfer of your interest may be an option. If there is an agreement, a joint sale usually makes the transaction much easier.

4. **If the disagreement is structural, consider the division of common property**

When the property is essentially indivisible, Article 404 of the Civil Code provides that, if the co-owners do not agree to assign it to one of them compensating the others, “it shall be sold and the price divided” Civil Code, art. 404.

When division replaces a unilateral sale of the whole

This is the key point if you are wondering what to do when you cannot reach agreement with the others. In co-ownership, no one should be indefinitely trapped in an indivisible property for lack of consensus. The Civil Code protects this route: if the common property cannot be divided usefully, it is possible to request its sale and the division of the proceeds.

However, it is worth distinguishing between two scenarios:

- **Property that can be divided into separate allocations**: if the building allows it, a physical division or an allocation of flats or units can be proposed.

- **Property that is indivisible or loses usefulness if divided**: it may end up being sold and the proceeds divided, or allocated to one of the co-owners with compensation to the others.

This does not mean that any co-owner can simply “force” an immediate sale of the whole property without further procedure. What exists is a route to request division or the termination of the joint ownership when there is no agreement. If the property cannot be usefully divided, the legal solution is to sell and divide the price, not to ignore the other owners.

What you should check before taking the step

The most practical part is not only legal, but documentary and strategic. Before moving ahead with the transaction, it is advisable to review certain points to avoid mistakes that later complicate the sale and purchase.

### Practical advice

- **Make it clear in writing exactly what you are selling**: an undivided share is not the same as the whole property.

- **Identify all co-owners**: any negotiation will be much more efficient if you know who you need to deal with.

- **Check whether there are charges or restrictions on your share**: mortgages, attachments or other conditions may affect the transaction.

- **Do not market the property as if it were a full sale if you are only selling part of it**: that can create false expectations and disputes.

- **If there is scope for agreement, propose an agreed exit first**: it is usually quicker and less costly than a prolonged dispute.

### Common mistakes

1. **Confusing an undivided share with exclusive ownership**

This is the most common mistake and the one that causes the most problems in negotiations.

2. **Thinking you can sell the whole property without the consent of the others**

If you are not the sole owner, you cannot dispose of the whole as if it were exclusively yours.

3. **Ignoring the route of division of common property**

When there is deadlock, this route may be the right answer if the legal requirements are met.

4. **Failing to separate the legal solution from the commercial one**

Even if there is a right to act, it will not always be easy to find a buyer for a share. The strategy must be carefully considered.

How UBICASA can help if you want to organise the transaction

If you find yourself in this situation, the wisest approach is to start with a clear review of the ownership and the best possible route: sale of your share, negotiation with the other co-owners or preparation for a possible division.

You can request an indicative valuation of the property in Madrid at /valoracion-vivienda-madrid. The online estimate is indicative, does not constitute an official valuation, and includes a price range and a PDF report; it can also be complemented by a visit if needed.

If you would prefer to discuss your case before making decisions, you can contact us via /contacto.

The UBICASA office is at Calle Montesa 29, Madrid, with opening hours Monday to Friday from 10:00 to 15:00 and from 16:00 to 19:00.

In short, if you only own part of the flat, you cannot unilaterally sell the entire property, but you do have room to act: sell your share, negotiate with the others or pursue division when the common property cannot be maintained by agreement. The key is to identify the legal situation correctly and choose the appropriate route to avoid unnecessary deadlock.