Double Tax Treaty (Convenio de Doble Imposición)

What Is a Double Tax Treaty?

A Double Tax Treaty (CDI — Convenio de Doble Imposición) is a bilateral agreement signed between Spain and another state that allocates taxing rights over cross-border income. Spain has one of the world’s most extensive treaty networks, with more than 100 treaties in force covering virtually all major trading and investment partner countries, including the UK, US, Germany, France, the Netherlands, China, and most of Latin America.

Treaties follow either the OECD Model Convention or the UN Model Convention (the latter typically applies to treaties with developing countries and gives more taxing rights to the source country).

What Do Treaties Cover?

Reduced Withholding Tax Rates: A Practical Example

Under domestic Spanish law, the standard withholding rate on dividends paid to non-residents is 19%. Under the Spain–UK treaty, the rate is reduced to 10% (or 0% for companies with a 10%+ stake held for 12 months). Under the Spain–Netherlands treaty, the dividend withholding can be reduced to 0% for qualifying corporate shareholders. These differences make treaty planning a central element of investment structuring into Spain.

Claiming Treaty Benefits: The Certificate of Fiscal Residence

To benefit from reduced treaty rates, the recipient of Spanish-source income must typically provide:

1. A certificate of fiscal residence issued by the tax authority of their country of residence, confirming they are a tax resident there for purposes of the treaty.
2. A declaration that the recipient is the beneficial owner of the income (not acting as an agent or conduit).

These documents must be provided to the Spanish payer before the payment is made (so the reduced rate can be applied at source) or submitted to the AEAT as part of a refund claim if the full rate was already withheld.

Permanent Establishment Risk

One of the most important concepts in any treaty is the Permanent Establishment (PE). If a foreign company has a PE in Spain — a fixed place of business, a dependent agent, or a construction project exceeding a certain duration — Spain may tax the profits attributable to that PE as if it were a Spanish company, regardless of where the company is formally incorporated.

Common PE risks include: a foreign company’s employee working from Spain, a Spanish sales agent with authority to conclude contracts, or a project lasting beyond the treaty’s construction PE threshold (typically 12 months under the OECD model, sometimes 6 months under the UN model).

The Multilateral Instrument (MLI)

Spain has ratified the OECD Multilateral Instrument (MLI), which modifies many of its existing treaties simultaneously to incorporate BEPS minimum standards. The most significant change is the Principal Purpose Test (PPT), which allows treaty benefits to be denied if one of the principal purposes of an arrangement was to obtain those benefits. This makes substance and genuine commercial purpose essential for treaty planning.

How BMC Can Help

We advise on treaty eligibility for cross-border investment structures, prepare and manage treaty refund claims for overheld withholding tax, analyse PE exposure for foreign companies operating in Spain, and advise on the interaction between treaty provisions and Spanish domestic anti-avoidance rules.