Could a new Spanish government cancel the UK–EU treaty on Gibraltar?

Question

Accepted Answer

Not by itself. Spain is not a party to the treaty in its own right; the parties are the EU and the UK, either of which can end it with 12 months' written notice. Spain can also ask the EU to terminate it, but only after an evaluation of the border arrangements, which is first due after four years of implementation.
The 2026 UK/EU Treaty in relation to Gibraltar is an agreement between the European Union (with the European Atomic Energy Community) and the United Kingdom in respect of Gibraltar. Spain took part in the negotiations but is not a separate party, so a Spanish government cannot cancel it directly.
The treaty provides several ways in which it can be suspended or ended:
Termination on notice: either the UK or the EU can terminate the treaty by written notification, taking effect 12 months later (Article 334).
Spain's request: the Commission's proposal for the Council decision concluding the treaty provides that Spain, as the state carrying out Schengen border control at Gibraltar's port and airport, may request the EU to terminate the treaty after an evaluation of the part dealing with the circulation of persons. That evaluation takes place after an initial four years of implementation. Separately, decisions to suspend the treaty or take remedial or safeguard measures are taken on the EU side by the Commission in consultation with Spain. The Spanish Government has described this as Spain having the initiative to suspend, apply safeguards or terminate.
Serious breach: if either party considers there has been a serious and substantial failure by the other to meet obligations described as essential elements, it may terminate or suspend the treaty in whole or in part, after following the required procedure.
Failure to apply EU rules: if Gibraltar does not apply a relevant EU act as required, the whole treaty is treated as terminated unless the Cooperation Council decides otherwise.
On the UK side, the UK Government has committed in a concordat with Gibraltar that, other than in the most exceptional circumstances, it will not terminate the treaty without the support of a majority of the Gibraltar Parliament or a referendum in Gibraltar.
Asked on Sunday 21 June 2026 whether a future Spanish government might seek to suspend the treaty, Gibraltar's Chief Minister, Fabian Picardo, said that every agreement must contain such a clause, but that the parties had not entered it planning how to leave, and that any politician who tried to bring less fluidity and less shared prosperity would be foolish.
In the sources reviewed, no Spanish party has said that it would ask the EU to terminate the treaty.

Could a new Spanish government cancel the UK–EU treaty on Gibraltar?

Short answer

Detailed answer

How the treaty can be suspended or ended

The UK side

The Gibraltar Government's view