Banco de Portugal Posts €42.4 Billion in Certificados de Aforro at End-May for a 20th Consecutive Monthly Climb — €750 Million Subscription Burst Marks a Three-Year High as Série F Pays Almost 2.2% and the €250,000 Cap Pulls Household Savings

The stock of Certificados de Aforro (Savings Certificates) closed May at €42.4 billion, an all-time high for the IGCP-managed retail-debt instrument and the 20th consecutive monthly increase, according to data released this Friday by the Banco de Portugal (Bank of Portugal). Net subscriptions in May alone reached around €750 million — the strongest single-month inflow in three years and a level not seen since the rate war of mid-2023 that the previous government broke by cutting the Série E coupon.

The acceleration places household-held public debt at a record share of Portugal's overall sovereign stack and reverses the slow leak that followed Mário Centeno's June-2023 decision to retire Série E. Série F, the current series rolled out in 2023 to replace Série E, is paying close to 2.2% on May subscriptions — the highest yield it has offered since May 2025 and a function of the recent rebound in three-month Euribor that anchors its monthly coupon reset.

Why subscriptions surged

Three factors are pulling household money into Aforro. First, in April 2026 the government raised the per-person subscription cap on Série F from €100,000 to €250,000, opening headroom for higher-net-worth savers who had previously bumped against the ceiling. Second, the monthly coupon recalibration on Série F has captured the recent Euribor uptick, lifting effective yields above the average term-deposit rate offered by the major retail banks (Caixa Geral de Depósitos, Millennium BCP, Novo Banco, Santander Portugal, BPI). Third, retail demand for safer instruments has lifted against a backdrop of EU equity-market volatility and political risk after the defeat of the Trabalho XXI labour reform earlier today.

How Série F works

Série F pays a base rate indexed to the three-month Euribor with a 1-percentage-point spread, recalibrated monthly. The instrument is sold at Correios (CTT) branches and through the AforroNet portal, with a minimum subscription of €100 and the new €250,000 per-titular cap. Interest is paid quarterly and is subject to a 28% IRS (income tax) withholding at source. Capital is guaranteed by the Portuguese Republic and is fully redeemable after a three-month minimum holding period.

What this means for expats

• Yield pickup over term deposits: At close to 2.2% net of fees but before tax, Série F is currently out-yielding the average three-month term deposit at Portugal's five biggest retail banks (which sit around 1.4-1.7% gross). For passive cash buffers, the gap is meaningful.
• Eligibility is open to foreign residents: Any individual with a Portuguese NIF (tax identifier) and a Portuguese bank account can subscribe through AforroNet. There is no nationality or residency requirement beyond the NIF and a domestic IBAN.
• The €250,000 cap is per titular: A married couple filing jointly can hold up to €500,000 in Série F across two accounts, useful for households restructuring liquidity after a property sale or pension payout.
• 28% withholding applies, but there is no wealth tax: Interest is taxed at the standard IRS rate for capital income (28% flat, unless englobamento — joint declaration — produces a lower marginal rate). Non-habitual residents on the older NHR regime can also subscribe, but the tax treatment of Aforro interest depends on the bilateral tax treaty with the country of fiscal residence.
• Liquidity caveat: Aforro is fully liquid after three months but a partial redemption inside the year forfeits accrued interest above the indexed base. Treat it as a 12-month parking instrument, not as an overnight reserve.

For the State, the rebound is double-edged. On the one hand, retail-debt financing reduces dependence on wholesale OT (Obrigações do Tesouro) issuance and lengthens the average maturity of the debt stack. On the other, the €750 million monthly inflow is a comparatively expensive funding source — Série F coupons now sit above the secondary-market yield on 5-year Portuguese OTs. The IGCP, which manages the country's public debt, will need to recalibrate its 2026 issuance plan if the inflow pace holds through Q3.