If you are tax resident in Spain, your bank accounts, investments and property in Mexico must be declared to the Spanish tax authorities on form 720 once any of the blocks exceeds 50,000 euros, even where those assets generate no income in Spain. It is an informative return, not a tax: filing it produces nothing to pay, but the obligation remains fully in force.
Who it binds: whoever resides in Spain
You often hear that, if assets in Mexico produce no income in Spain, the tax authorities have no business knowing about them. That is not so. The General Tax Act imposes the obligation to report assets and rights located abroad, and the regulation implementing it places that obligation on individuals and legal entities resident in Spanish territory. What triggers the obligation is residence, not the source of the income.
The Personal Income Tax Act treats a person as habitually resident in Spain where, among other cases, they spend more than 183 days of the calendar year in Spanish territory; for that count, sporadic absences are included unless tax residence in another country is evidenced. A person is also resident where the main centre or base of their activities or economic interests is in Spain. Someone from Mexico who settles in Spain therefore becomes subject to the obligation from the first year of residence if any of their blocks exceeds the threshold, even though all their assets remain in Mexico.
There is one exception: according to the criterion of the Spanish tax authorities, persons under the special regime for posted workers of article 93 of the Personal Income Tax Act are not obliged to file (their resident family members are).
Three blocks, three thresholds of 50,000 euros
Form 720 does not look at your assets as a whole. It is declared by blocks, and each has its own threshold:
- Accounts at financial institutions located abroad.
- Securities, rights, insurance and annuities deposited, managed or obtained abroad.
- Property and rights over property located abroad.
Within each block, if the combined value does not exceed 50,000 euros, there is no obligation to report on that block. If it is exceeded, all the assets making it up must be reported, not just the one that pushes the figure over. For accounts, two reference points are taken: the balance at 31 December and the average balance for the last quarter of the year; it is enough for either of them, adding all the accounts together, to exceed 50,000 euros for all of them to have to be declared.
A property counts at its acquisition value, not what it is worth today. For a house bought in Mexico years ago, the relevant figure is its acquisition value, which sometimes leaves the block below the threshold even though the current market value is much higher, and at other times means reconstructing from documents a date and a value nobody had to hand.
When it is filed, and when it need not be repeated
The return is filed between 1 January and 31 March of the year following the one the information relates to. So assets held at 31 December 2026 are declared between January and March 2027.
It does not have to be repeated every year. In later years it becomes compulsory again in only two cases: where the combined value of a block has increased by more than 20,000 euros over the figure that determined the last return filed, or where you cease to hold an asset you had already declared.
Three mistaken ideas
That it is a tax
Form 720 is an informative return: it consists of supplying the tax authorities with information about assets located abroad. Filing it produces no amount to pay. The taxation of the income from those assets (interest, dividends, rental income) is a different matter: personal income tax for a resident is charged on the whole of their income regardless of where it arose, and that is a separate obligation.
That Europe struck it down
In its judgment of 27 January 2022 (case C-788/19), the Court of Justice of the European Union declared contrary to EU law the special consequences attached to form 720: the treatment of undeclared assets as unjustified capital gains with no limitation period, and the specific penalties. Law 5/2022 removed those consequences, but kept the reporting obligation.
That only accounts in your own name count
The obligation covers accounts you hold, but also those where you appear as representative, authorised signatory or beneficiary, or over which you have powers of disposal. Worth checking if you are still an authorised signatory on a relative's account in Mexico.
What to gather before the first year
The practical difficulty is rarely the form: it is the data from Mexico. For property you need the date and value of acquisition; for accounts, the balances at 31 December and the average balance for the last quarter; for investments, the intermediary's documentation. Having the deeds and statements in order before January avoids declaring with approximate figures.
Common mistakes
- Thinking that with no income in Spain there is nothing to declare. The obligation arises from tax residence.
- Adding up all your assets into a single figure. Each block has its own 50,000 euro threshold.
- Valuing the house in Mexico at market price. What is declared is the acquisition value.
- Forgetting accounts where you are an authorised signatory. They are declared too.
- Believing it no longer exists after the European judgment. What was removed were those special consequences, not the obligation.
Sources
- Law 58/2003, of 17 December, General Tax Act, eighteenth additional provision (consolidated text from the BOE, consulted in September 2026)
- Law 35/2006, of 28 November, on Personal Income Tax, articles 2 and 9.1 (consolidated text from the BOE, consulted in September 2026)
- Royal Decree 1065/2007, of 27 July, articles 42 bis, 42 ter and 54 bis (consolidated text from the BOE, consulted in September 2026)
- Law 5/2022, of 9 March, preamble, section IV
- Judgment of the Court of Justice of the European Union of 27 January 2022, case C-788/19, Commission v Spain
- Law 5/2022, fourth and fifth final provisions (consolidated text from the BOE, consulted in September 2026)
- Spanish Tax Agency, form 720 frequently asked questions: who must file (consulted in September 2026)