Q2 2026 Interest Rate: How It Affects Your Fixed Income Assets

Key data

If you hold treasury bills, bonds, debentures or other fixed income securities in your portfolio, this quarter you have a specific tax obligation: correctly applying the effective annual interest rate published by the Secretaría General del Tesoro to classify those assets for tax purposes. The Resolución de 25 de marzo de 2026 (BOE-A-2026-7183) establishes this reference rate for the second natural quarter of 2026, effective from April 1.

This is not a minor change. The classification resulting from applying this rate determines the withholding tax regime and the way in which capital income is reported, with different consequences depending on whether the taxpayer is an individual or a legal entity.

What does this regulation establish?

The Secretaría General del Tesoro publishes a quarterly effective annual interest rate that acts as a reference threshold for classifying fixed income financial assets for tax purposes. The key distinction is between two types of yield:

• Explicit yield: The asset pays periodic interest separately from the principal. Withholding tax is applied at the time those interest payments are made.
• Implicit yield: The return is incorporated into the difference between the issue or acquisition price and the redemption or transfer price. Taxation occurs at the time of sale or maturity, not before.

The rate published by the Treasury for each quarter is the criterion that determines which of these two categories each specific asset falls into. This classification is not optional: it is the basis on which withholding taxes are calculated and the corresponding tax returns are completed.

The instruments expressly mentioned in the regulation as subject to this classification are:

• Treasury bills (Letras del Tesoro)
• Bonds (Bonos)
• Debentures (Obligaciones)
• Other fixed income securities

Economic and operational impact

The impact of this resolution is not abstract. It affects specific treasury, accounting and tax compliance decisions during the months of April, May and June 2026.

From an operational standpoint, the most relevant effects are:

• Withholding taxes: If an asset is reclassified from explicit to implicit yield (or vice versa) compared to the previous quarter, the timing at which withholding must be applied changes. This affects cash flows and quarterly withholding tax settlements.
• Tax returns: Correct classification is essential for properly completing modelo 193 (annual summary of withholding taxes on capital income) and the corresponding quarterly returns.
• Corporate investment portfolios: Companies holding fixed income portfolios must ensure that their accounting systems apply the correct criteria for Q2 2026, especially if they manage assets with maturities or planned transfers during this quarter.
• Financial institutions: As payers or intermediaries, they are obliged to apply the correct withholding taxes based on the classification resulting from applying the Treasury rate. An error in classification can lead to incorrect withholding and the corresponding tax liability.

Who is affected?

This resolution affects any individual or legal entity operating with fixed income assets during the second quarter of 2026. Specifically:

• Individual investors (natural persons) holding treasury bills, bonds or debentures that mature or are transferred between April and June 2026.
• Companies with fixed income asset portfolios that must classify their investments for tax purposes at the end of the quarter or for buy/sell transactions.
• Financial institutions (banks, fund managers, intermediaries) acting as payers of income or applying withholding taxes on these instruments.
• Tax and accounting advisors managing client portfolios with fixed income assets who must apply the correct rate in their tax returns.
• Treasurers and CFOs of companies investing surplus cash in short-term fixed income instruments, such as treasury bills.

Practical example

A mid-sized company invests surplus cash in treasury bills maturing in May 2026. At the time of redemption, it must determine whether the yield obtained qualifies as implicit or explicit yield for tax purposes.

To do so, it applies the effective annual interest rate published by the Treasury for the second quarter of 2026 (effective from April 1). If the effective return on the bill exceeds that threshold, the asset is classified one way; if it does not, it is classified another way. This classification determines:

• Whether withholding tax must be applied at the time of redemption or whether it was already applied at an earlier point.
• How the yield must be reflected in the Corporate Income Tax (Impuesto sobre Sociedades) return for the 2026 financial year.
• What information must be included in modelo 193 at year-end.

An error in this classification can result in incorrect withholding taxes, requiring the submission of supplementary returns and potentially generating surcharges or late payment interest before the Agencia Tributaria.

What should companies do now?

1. Identify fixed income assets in the portfolio with maturity or planned transfer between April 1 and June 30, 2026: treasury bills, bonds, debentures and other similar securities.
2. Apply the effective annual interest rate published by the Secretaría General del Tesoro for Q2 2026 to each asset, to determine whether its yield qualifies as implicit or explicit in accordance with Resolución BOE-A-2026-7183.
3. Review the withholding tax obligations applicable to each asset based on its classification, and verify that accounting and tax systems are correctly configured for the quarter.
4. Coordinate with the tax advisor to correctly complete the quarterly withholding tax returns and the annual summary (modelo 193), incorporating the classification resulting from applying the Q2 2026 rate.
5. Document the classification applied to each asset during this quarter, as supporting evidence in the event of an audit by the Agencia Tributaria.

Official source

View full regulation at the official source

Disclaimer: This article is for informational purposes only and does not constitute legal advice. For specific decisions, please consult a qualified professional. Source: https://www.boe.es/diario_boe/txt.php?id=BOE-A-2026-7183