Spain-US DTT Article 11 — Interest Income: The 10% Cap, Beneficial Ownership, and FATCA Reporting

Cross-border interest payments between Spain and the United States are among the most common transactions encountered in international tax practice: Spanish residents earning interest on US Treasury bonds or savings accounts; US lenders providing financing to Spanish subsidiaries; Spanish banks holding deposits from American clients. Article 11 of the 1990 Spain-US Convention for the Avoidance of Double Taxation governs which country may tax those payments and at what rate. Getting the analysis wrong leads to over-withholding, double taxation, or — if treaty benefits are claimed incorrectly — penalties and interest assessments on both sides of the Atlantic.

This article examines every dimension of Article 11 in depth: the allocation of taxing rights, the definition of "interest," the beneficial ownership requirement, practical examples for both inbound and outbound flows, the saving clause for US citizens, Spanish IRNR obligations, anti-hybrid rules, and the FATCA reporting framework. It also addresses the zero-withholding exceptions found in the Protocol and the interplay with Spain's thin capitalisation rules.

Article 11 Overview: The Basic Allocation of Taxing Rights

Article 11 establishes a shared taxing jurisdiction. Unlike dividends under Article 10, where the residence country has primary rights and the source country is limited to a reduced withholding rate, interest under Article 11 follows a similar model: the residence country retains the primary right to tax — it may impose full personal income or corporate tax on the gross or net interest received — while the source country (the country in which the interest originates) is entitled to withhold, but only up to 10% of the gross amount of the interest.

This cap of 10% is a substantial reduction from the domestic rates that would otherwise apply. In Spain, non-resident interest income is generally subject to IRNR (Impuesto sobre la Renta de No Residentes) at 19% for EU/EEA residents and 24% for residents of non-EU countries, including the United States under domestic law. In the United States, the default withholding rate on portfolio interest paid to foreign persons is 30% under IRC § 1441, though portfolio interest paid on certain US bonds is exempt under the portfolio interest exemption. Article 11's 10% cap therefore provides meaningful treaty benefits where the exemption does not apply.

The structure of Article 11 mirrors the OECD Model Tax Convention, with modifications negotiated between Spain and the US. The key provisions are:

• Article 11(1): Interest arising in one state and paid to a resident of the other state may be taxed in the residence state.
• Article 11(2): That same interest may also be taxed in the source state, but the tax so charged may not exceed 10% of the gross amount of interest if the recipient is the beneficial owner.
• Article 11(3): Definition of "interest" for treaty purposes.
• Article 11(4): Source rule — interest is deemed to arise in a Contracting State when the payer is a resident of that state or has a permanent establishment there that bears the interest expense.
• Article 11(5): Anti-avoidance provision for artificially high interest rates between connected persons.

What Counts as "Interest" Under Article 11

Article 11(3) of the Convention defines interest broadly as income from debt claims of every kind, whether or not secured by a mortgage and whether or not carrying the right to participate in the debtor's profits. This includes:

• Income from government bonds and corporate bonds (including US Treasury bonds, US savings bonds, and Spanish bonos del Estado or obligaciones)
• Income from debentures and other forms of fixed or variable-rate debt securities
• Income from mortgage debt and promissory notes
• Interest on bank deposits and current accounts
• Interest on intercompany loans and intra-group financing arrangements
• Penalty interest for late payment, where characterised as interest rather than damages under the applicable domestic law
• Any income assimilated to income from money lent by the taxation law of the state in which the income arises

The final category — income assimilated to loans under domestic law — is the broadest and most technically demanding. Spain's domestic tax law (the Ley del Impuesto sobre la Renta de No Residentes, LIRNR) can characterise certain financial instruments as debt rather than equity, bringing associated payments within Article 11 even if the instrument does not look like a conventional loan. This is particularly relevant for hybrid financial instruments, discussed further below.

The Beneficial Ownership Requirement

The 10% source-country withholding cap is not available to every recipient of interest. Article 11(2) limits the reduced rate to situations where the recipient of the interest is the beneficial owner — not merely the legal or nominal recipient. This is an explicit anti-conduit rule designed to prevent treaty shopping: a person cannot route interest through an intermediate entity resident in Spain or the US in order to claim the 10% cap when the true economic beneficiary is a resident of a third country.

Beneficial ownership is not defined in the Convention itself. The OECD Commentary — which Spanish courts and the DGT use as interpretive guidance — provides that a recipient is not the beneficial owner if it merely acts as an agent or nominee for another person, or if it is a conduit company that passes through the interest with little or no discretion and is obligated (formally or informally) to transmit the interest to a third party. The OECD 2014 update to the Commentary strengthened this position, making clear that a conduit's formal legal title is insufficient to establish beneficial ownership where economic control lies elsewhere.

For Spanish tax purposes, the AEAT will examine the substance of the recipient entity: does it have employees, premises, decision-making capacity, and genuine economic activity? A holding company incorporated in Spain that receives interest from a US subsidiary and immediately on-pays it to a Luxembourg parent under a back-to-back loan arrangement will likely be denied beneficial owner status by the AEAT, with the full 30% US domestic withholding rate reinstated.

Practical Example 1: Spanish Resident Earning US Interest

Consider María, a Spanish tax resident who holds USD 500,000 in a US brokerage account, invested in a mix of US Treasury bonds and a US savings account. In 2025 the account generates USD 18,000 of interest income.

Step 1 — US withholding. The US paying agent is required to withhold on interest paid to a foreign person. Under the treaty, the rate is capped at 10%, provided María has filed a Form W-8BEN (Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding) with the US brokerage. The W-8BEN certifies María's Spanish residency, claims the Article 11 treaty rate, and provides her Spanish tax identification number (NIF). Without a properly completed W-8BEN on file, the US payer may withhold at the default 30% rate. With the W-8BEN in place, US withholding is USD 1,800 (10% of USD 18,000).

Note: US Treasury portfolio interest may be exempt from US withholding under the portfolio interest exemption (IRC § 871(h)) even without a treaty. However, María still needs the W-8BEN to claim that exemption, and the treaty provides a backstop for interest not qualifying for the exemption.

Step 2 — Spanish taxation. Spain taxes María's worldwide income as a Spanish resident. The USD 18,000 of interest is classified as rendimientos del capital mobiliario (income from movable capital) and is included in the base del ahorro (savings income base) under Article 25 LIRPF. In 2025 the savings income rates are 19% on the first EUR 6,000, 21% on EUR 6,000–50,000, 23% on EUR 50,000–200,000, 27% on EUR 200,000–300,000, and 28% above EUR 300,000.

Step 3 — Credit mechanism. Spain grants a credit for foreign taxes actually paid (deducción por doble imposición internacional, Article 80 LIRPF). María may deduct the USD 1,800 withheld in the US from her Spanish IRPF liability on the same income, up to the amount of Spanish tax that would have been charged on that same income. Double taxation is substantially (though not always fully) eliminated through this mechanism.

Step 4 — Reporting. María reports the interest on her Spanish IRPF return (Modelo 100). She must also consider whether the US account must be reported on Modelo 720 (foreign assets declaration) if the aggregate value exceeds EUR 50,000 and whether the account is reportable under FATCA to the IRS through the Spanish-US FATCA IGA.

Practical Example 2: US Lender Receiving Spanish Interest

Now consider TechCorp LLC, a US company that has lent EUR 2,000,000 to its Spanish subsidiary, Filial SL, at a fixed interest rate of 5% per annum. Annual interest payments are EUR 100,000.

Step 1 — Spanish IRNR withholding. Filial SL is required to withhold IRNR on interest payments to non-resident creditors. Under domestic Spanish law (LIRNR), the withholding rate for non-EU residents is 24% — meaning Filial SL would withhold EUR 24,000 on a EUR 100,000 payment absent a treaty. Under Article 11 of the Spain-US Convention, the rate is capped at 10%, reducing the withholding to EUR 10,000. Filial SL pays TechCorp EUR 90,000 net and remits EUR 10,000 to the AEAT via Modelo 216 (monthly non-resident withholding return) and summarises the position on Modelo 296 (annual summary).

TechCorp must have provided Filial SL with its certificate of US tax residency (typically an IRS Form 6166 — Certificate of US Tax Residency) to claim the treaty rate. Without it, Filial SL's conservative approach is to apply the 24% domestic rate.

Step 2 — US taxation. TechCorp includes EUR 100,000 (converted to USD) in its US taxable income. It may claim a foreign tax credit under IRC § 901 for the EUR 10,000 of Spanish IRNR withheld, reducing its US tax liability accordingly. The foreign tax credit is limited to the US tax on the same category of income (the "basket" rules under IRC § 904), but for ordinary loan interest the credit usually absorbs the Spanish tax in full.

Step 3 — Transfer pricing. The 5% rate must be arm's length. If the AEAT determines on audit that an independent lender would have charged 3%, it may disallow the excess EUR 40,000 of interest as a deductible expense for Filial SL and reclassify it as a hidden dividend distribution (dividendo encubierto) under Article 16 LIS (Ley del Impuesto sobre Sociedades), attracting Article 10 withholding rather than Article 11. The arm's length analysis for intra-group loans must be documented in Filial SL's transfer pricing file.

The Saving Clause: US Citizens Are Always Taxable in the US

Article 1(4) of the Spain-US Convention contains the saving clause, which provides that notwithstanding any other provision of the Convention, a Contracting State may tax its residents and citizens as if the Convention had not come into force. For US citizens, this has a direct impact on Article 11 planning.

A US citizen who is resident in Spain — and thus would ordinarily be taxed on Spanish-source interest only up to the 10% withholding rate, with Spain taxing the residual — cannot use the treaty to reduce or eliminate US tax on that same interest. The US will tax the full amount of Spanish interest income on the US Form 1040, with a credit for the Spanish IRPF or IRNR paid. The saving clause prevents a US citizen from arguing that because Spain has primary taxing rights under Article 11(1), the interest is exempt from US taxation.

In practice, US citizens living in Spain will report Spanish-source interest twice: once on their Spanish IRPF return (Modelo 100) and once on their US Form 1040. The foreign tax credit mechanisms in both countries — Spain's Article 80 LIRPF credit and the US IRC § 901 foreign tax credit — reduce but rarely eliminate the combined tax burden completely, particularly when the Spanish savings income rates (up to 28%) exceed the effective US rate on the same income.

Spanish IRNR — Modelo 210 for Non-Residents

A non-resident individual or entity receiving interest from Spanish sources (Spanish bank deposits, Spanish corporate bonds, Spanish mortgage loans) is subject to IRNR. Where the Spanish payer does not withhold — for example, in private lending arrangements between non-residents and Spanish individuals — the non-resident recipient must self-assess the IRNR by filing Modelo 210 (Non-Resident Income Tax Return).

Under the treaty, the IRNR rate on interest is 10% of the gross amount. The Modelo 210 must be filed quarterly (for each quarter in which income was received) or, if the income is subject to retención (withholding at source by the Spanish payer), the withholding itself satisfies the IRNR obligation and a separate Modelo 210 is not required.

Non-residents who are US tax residents must ensure they are treated as US residents for treaty purposes — having a Form 6166 or equivalent documentation available — to claim the 10% treaty rate rather than the 24% domestic IRNR rate. The deadline to file Modelo 210 for quarterly non-withheld income is the 20th of the month following the end of the quarter.

Spanish Banks' Obligation to Withhold for Non-Resident Account Holders

Under Spanish law, banks and financial institutions are obligated to withhold IRNR on interest credited to accounts held by non-residents. The withholding rate under domestic law is 19% for EU/EEA residents and 24% for others. However, when a non-resident presents their treaty entitlement — typically by providing the bank with their foreign tax identification number, a certificate of residence in the treaty country, and completing the bank's internal treaty claim form — the bank should apply the 10% treaty rate.

In practice, Spanish banks often apply the 19% or 24% domestic rate and leave the non-resident to file a Modelo 210 refund claim (devolución de IRNR) for the excess withholding. The refund claim is filed using Modelo 210 with the "devolución" option selected, and the AEAT typically processes refunds within six months, though delays of 12–18 months are not uncommon for claims involving large amounts or complex treaty analysis.

Form W-8BEN: Claiming the 10% Rate from US Payers

Form W-8BEN (Certificate of Foreign Status of Beneficial Owner for United States Tax Withholding and Reporting — Individuals) is the primary mechanism by which a Spanish resident certifies their non-US status and claims a reduced withholding rate under the treaty when receiving US-source interest. The equivalent for entities is Form W-8BEN-E.

Key information required on Form W-8BEN includes:

• Full legal name and country of citizenship
• Permanent address (which must be in Spain, not a US address or a P.O. box)
• Spanish tax identification number (NIF) in the "Foreign TIN" field
• The treaty country (Spain) and the specific treaty article claimed (Article 11) with the reduced rate (10%)
• Certification that the filer is the beneficial owner of the income and is not a US person

Form W-8BEN is valid for three calendar years from the year of signing, unless the circumstances change (for example, if the filer becomes a US resident). It must be renewed before expiry to maintain the reduced withholding rate. US payers (banks, brokerages, corporate bond issuers) are required to retain the form and are subject to IRS audit for improperly reduced withholding.

FATCA and Interest Reporting: Form 1042-S

The Foreign Account Tax Compliance Act (FATCA), enacted in 2010 and in force between Spain and the US under the 2013 Spain-US FATCA Intergovernmental Agreement (IGA, Model 1), creates a bilateral reporting framework for interest and other income paid to foreign persons and foreign financial institutions.

From a US-payer perspective, interest paid to Spanish residents (who are "foreign persons" for US tax purposes) is reportable on Form 1042-S (Foreign Person's US Source Income Subject to Withholding). Form 1042-S must be filed with the IRS and provided to the recipient by 15 March of the year following the calendar year of payment. The form reports the gross amount of interest, the treaty withholding rate applied (10%), the amount withheld, and the recipient's identification details including their foreign TIN.

From a Spanish bank perspective, under the FATCA IGA, Spanish financial institutions report accounts held by US persons (US citizens or US tax residents) to the AEAT, which in turn transmits the information to the IRS. This means interest credited to accounts held by US citizens in Spanish banks is automatically reported to the IRS — eliminating any possibility of inadvertent non-disclosure of Spanish interest income on a US Form 1040.

Zero Withholding Exceptions in the Protocol

The Protocol to the Spain-US Convention, which forms an integral part of the treaty, contains several zero-withholding exceptions that reduce the source-country rate from 10% to 0% for certain categories of payers and recipients. These exceptions reflect the principle that government entities and certain tax-favoured vehicles should not face cross-border withholding on interest income.

For Spanish pension funds (fondos de pensiones) receiving interest from US sources, the zero-withholding exception is particularly valuable. A Spanish occupational pension fund that holds US corporate bonds earning USD 500,000 per annum would, without this exception, face USD 50,000 of US withholding at the 10% treaty rate. The Protocol exception eliminates this entirely, provided the fund provides documentation of its tax-exempt pension status to the US payer.

Intercompany Loans and Spain's Thin Capitalisation Rules

Where a Spanish entity pays interest to a related party (defined broadly as direct or indirect participation of 25% or more), Spain's transfer pricing provisions and the thin capitalisation framework in Article 16 LIS apply to prevent artificial deduction of interest. Under the interest limitation rule (regla de limitación de la deducibilidad de gastos financieros), a Spanish company may only deduct net financial expenses up to 30% of its operating EBITDA in the tax period, with a minimum deductible amount of EUR 1,000,000 (Article 16(1) LIS, as amended by Law 27/2014).

Where the interest rate charged on an intra-group loan exceeds the arm's length rate — or where the debt level is excessive relative to the borrower's equity — the AEAT may reclassify excess interest payments as deemed dividends. A reclassification as dividend has treaty consequences: Article 10 applies rather than Article 11, the withholding rate may differ (15% for dividends versus 10% for interest in the general case), and the deduction in the paying entity is lost, increasing its Spanish corporate tax liability.

Anti-Hybrid Rules — ATAD II in Spain

Spain implemented the EU Anti-Tax Avoidance Directive II (ATAD II) through the Ley 5/2022, introducing anti-hybrid rules in Article 15 bis LIS effective from 1 January 2022. These rules target hybrid mismatch arrangements — situations where a financial instrument is treated differently by two jurisdictions, for example as debt (producing deductible interest) in one country and equity (exempt dividend) in the other.

The classic hybrid interest scenario: a US company issues a convertible instrument to its Spanish subsidiary that Spain classifies as debt (so the Spanish entity deducts the "interest" paid to the US parent), while the US treats the same payments as equity distributions not included in the US parent's taxable income under the participation exemption or check-the-box rules. Under ATAD II's anti-hybrid rules, Spain will deny the deduction for the Spanish entity's interest payments to the extent the corresponding payment is not included in the US recipient's taxable income in the US.

The practical consequence for Article 11 planning: a payment that qualifies as "interest" under the treaty definition may still be non-deductible in Spain if the anti-hybrid rules apply. The treaty withholding cap (10%) continues to govern the source-country rate, but the economic benefit of the deduction — which is what drives the financing structure — may be neutralised. Structures involving hybrid instruments between US and Spanish entities must be reviewed under both the treaty characterisation rules and the ATAD II anti-hybrid provisions.

Bank Interest vs Bond Interest vs Private Lending: Practical Differences

Bank Deposit Interest

Interest from bank deposits held in Spain by non-resident US citizens is subject to IRNR withholding at source by the bank. The bank applies the treaty rate (10%) if the customer has provided treaty documentation, or the domestic rate (24% for US residents) otherwise. The withholding is the final tax for most non-residents — no further Spanish return is required unless claiming a refund of excess withholding.

Bond Interest

Interest on Spanish government bonds (Letras del Tesoro, Bonos, Obligaciones) or Spanish corporate bonds paid to non-resident US investors is subject to IRNR at the 10% treaty rate, with the paying agent (typically the Banco de España or a securities depository) applying the withholding. US bondholders must register their tax status with the Spanish paying agent to receive the treaty rate; failing to do so results in 24% withholding with a subsequent refund claim required.

Private Lending

Interest on privately negotiated loans between individuals or non-bank entities does not benefit from automatic withholding infrastructure. The Spanish borrower must apply and remit IRNR withholding on behalf of the non-resident lender (Modelo 216 / 296 for corporate borrowers) or the non-resident must self-assess via Modelo 210. Private lending arrangements often fall outside routine compliance processes, creating disproportionate audit risk.

DGT Criterion on Interest Characterisation: Interest Characterisation

The Dirección General de Tributos issued DGT binding ruling on interest characterisation addressing the characterisation of payments made under a cross-border financial arrangement between a Spanish company and its US parent. The DGT confirmed that for a payment to qualify as "interest" under Article 11 of the Spain-US Convention, it must arise from a genuine debt claim — the arrangement must create a legally enforceable obligation to repay principal, separate from any equity participation in the debtor's profits.

The consulta also addressed the boundary between Article 11 (interest) and Article 10 (dividends) in the context of participating loans (préstamos participativos). The DGT held that where a loan instrument provides for a variable return indexed exclusively to the borrower's profits, and there is no unconditional right to repayment of principal in insolvency, the payments may be reclassified as dividends rather than interest, regardless of the instrument's formal legal classification as a loan under Spanish commercial law. This interpretation has significant implications for hybrid instruments and mezzanine financing structures commonly used in US private equity investment in Spain.

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