Certificados de Aforro Simulator: Série F Rate and Tax

How this works

Série F adds two parts: the base rate, which follows 3-month Euribor with a 2.5% ceiling, and a permanence bonus that grows with the years held. Interest falls due every quarter at the annual rate divided by 4; IGCP withholds 28% IRS and only the net interest keeps earning. The simulator repeats this quarter by quarter with a constant base rate, which you can change to test scenarios.

1
The base rate changes every month
It is set on the third-to-last business day of each month, for the following month: the 3-month Euribor average over the previous 10 business days, rounded to 3 decimals, never below 0% or above 2.5%. For October 2026 it is 2.500%.
2
Each quarter gets its own rate
A quarter's rate is the base rate in force in the month that quarter starts, plus the bonus for the year held: 0.25 points in years 2 to 5, 0.50 in years 6 to 9, 1.00 in years 10 and 11, 1.50 in years 12 and 13 and 1.75 in years 14 and 15.
3
Only net interest compounds
On each quarterly interest date, gross interest is the accumulated value × rate ÷ 4. IGCP withholds 28% IRS and adds the remaining 72% to the certificate, where it earns interest from the next quarter.
4
Only full quarters count on redemption
You can redeem all or part from the first interest date, 3 months after subscribing. Days since the last interest date earn nothing, so the simulator counts only full quarters.

Worked example: €10,000 for 5 years

Using the October 2026 base rate, 2.5%, unchanged in every quarter. These are the values the simulator starts with.

Year 1: 2.5% ÷ 4 = 0.625% per quarter. The first gross interest is €62.50, IRS takes €17.50 and €45.00 compounds. After 4 quarters the certificate is worth €10,181.22.
Years 2 to 5: the 0.25-point bonus lifts the rate to 2.75%, which is 0.6875% gross and 0.495% net per quarter. Another 16 quarters take the value to €11,018.21.
Total: €1,414.18 gross interest, €395.97 IRS and a €1,018.21 net gain, equal to 1.96% net a year.

The «÷ 4» rule matches the CTT redemption table: a unit subscribed in June 2026, at a 2.215% base rate, was worth €1.00399 in September, exactly 1 + 2.215% ÷ 4 × 0.72. Counting calendar days would give €1.00402.

Redeem after the interest date, not the day before

Série F interest falls due every 3 months, on the same day of the month as the subscription. Redeeming before that day forfeits the current quarter: in the example above, the first quarter of year 2 is worth €50.40 net. To keep the interest, request redemption after the quarterly interest has fallen due. Redemption can be full or partial.

Certificados de aforro or a term deposit?

In August 2026, new household term deposits paid 1.63% gross a year on average (annualised agreed rate, Banco de Portugal). Série F pays 2.5% gross in year 1 and 2.75% in years 2 to 5, with the same 28% withholding: 1.80% and 1.98% net, against 1.17% for the average deposit. Against Série F: the rate is variable and falls if 3-month Euribor drops below 2.5%, and redeeming between interest dates forfeits that quarter's interest.

To simulate a fixed-rate deposit, use the compound interest calculator.

Série F vs Série E

Série E stopped taking subscriptions in June 2023, but existing holdings keep their rules until year 10. A Série E holding always pays more than a new Série F: the base has 1 extra point, the ceiling is higher and every subscription already gets a bonus.

	SÉRIE F	SÉRIE E
Base rate	3M Euribor, 0% to 2.5%	3M Euribor + 1 point, 0% to 3.5%
Permanence bonus	0.25 to 1.75 points (years 2 to 15)	0.5 (years 2 to 5) and 1.0 (years 6 to 10)
Term	15 years	10 years
Subscriptions	open since 5 June 2023	closed in June 2023
Limit per account	250,000 units	500,000 units with F and E combined

Frequently asked

What is the certificados de aforro rate in October 2026?

The rate is 2.500% gross a year for new Série F subscriptions, the maximum allowed, as published by IGCP on 30 September 2026. A subscription in years 2 to 5 adds 0.25 points and earns 2.75% in a quarter starting in October. No Série F subscription is above 2.75% yet: the series opened on 5 June 2023 and the 0.50 bonus only starts in year 6, from June 2028.

When can I redeem certificados de aforro?

Redemption is possible from the first interest date, 3 months after subscribing, in full or in part. You get the nominal value of the units plus interest already compounded; days since the last quarterly interest date are not paid. The money reaches the conta aforro IBAN within 7 days of the request. Without redemption, repayment is automatic on the 15th anniversary of the subscription.

How much IRS is paid on certificados de aforro interest?

Interest pays 28% IRS, withheld at source by IGCP on each quarterly interest date as a final tax (article 71 of the IRS Code). Residents can opt for englobamento (aggregation): the withholding becomes a payment on account, but the option means aggregating all capital income for that year. It only pays off when your marginal IRS rate is below 28%.

What is the maximum I can hold in certificados de aforro?

The maximum is 250,000 Série F units per conta aforro, which is €250,000, since 24 April 2026 (Despacho n.º 5392/2026). Including Série E, the ceiling per account is 500,000 units. Each person can hold only one conta aforro; each subscription has a minimum of 10 units (€10) and the account needs at least 100 Série F units.

Are certificados de aforro the same as certificados do tesouro?

No. Certificados de aforro pay interest every 3 months and can be redeemed after 3 months. Certificados do tesouro pay interest once a year and can only be redeemed after 1 year. This simulator applies only the Série F certificados de aforro rules.

I hold Série E. Should I redeem it to buy Série F?

Not for the rate. Série E is based on 3-month Euribor plus 1 point, with a 3.5% ceiling, and every subscription already gets a 0.5 or 1.0-point bonus; a new Série F starts at Euribor, with a 2.5% ceiling and no bonus in year 1. Also, redeeming Série E cannot be undone, because the series no longer accepts subscriptions.

What happens to the rate if Euribor falls?

The base rate follows the 3-month Euribor average and only stays at the ceiling while that average is above 2.5%. In 2026 it was 2.215% in June, 2.356% in July, 2.474% in August and 2.500% in September and October. To test a drop, change the base rate in the simulator: the calculation applies it to every quarter.

OFFICIAL SOURCES

IGCP · Taxas de juro dos certificados de aforro em outubro de 2026 ↗2.500% gross rate for new Série F subscriptions in October 2026 (published 30 September).
Diário da República · Portaria n.º 149-A/2023, versão consolidada ↗Creates Série F: base-rate formula and ceiling, permanence bonuses, compounding, redemption, term and current limits.
Diário da República · Despacho n.º 5392/2026 ↗Raises the maximum to 250,000 Série F units and 500,000 with Série E, effective 24 April 2026 (Despacho n.º 5839/2026).
IGCP · Ficha técnica da Série F ↗Official summary of the terms and subscription channels.
IGCP · Ficha técnica da Série E ↗3-month Euribor + 1 point base with a 3.5% ceiling, 0.5 and 1.0 bonuses and a 10-year term.
IGCP · Perguntas frequentes ↗Redemption from 3 months, with no interest since the last interest date; certificados do tesouro pay yearly.
CTT · Tabela de reembolso da Série F ↗Value per unit for each subscription month; confirms quarterly interest at the annual rate ÷ 4.
Portal das Finanças · Código do IRS, artigo 71.º ↗28% final withholding on capital income and the aggregation option for residents.
Portal das Finanças · Código do IRS, artigo 22.º ↗Opting for aggregation means aggregating all income of the same category.
Banco de Portugal · Taxa de juro de novos depósitos a prazo dos particulares ↗Average annualised agreed rate of 1.63% in August 2026.
euribor-rates.eu · Euribor a 3 meses ↗Daily 3-month Euribor values: 2.597% on 5 October 2026.
IGCP · Simulador Certificados de Aforro ↗Official simulator with the rates actually observed, to check a specific subscription.

DISCLAIMER

Informational simulation, checked on 6 October 2026 against Portaria n.º 149-A/2023 (consolidated version), the October 2026 rate published by IGCP and article 71 of the IRS Code. It assumes a single subscription, the same base rate in every quarter, full quarters only and 28% withholding. The real rate changes every month with Euribor; residents of the Azores and Madeira, non-residents and anyone opting for aggregation may face a different tax. IGCP calculates the value per unit, so the official amount can differ by a few cents. Not financial or tax advice: check AforroNet or the IGCP simulator.