What Are Portuguese Treasury Certificates? Série 5 Explained

What Treasury Certificates are

Treasury Certificates (Certificados do Tesouro) are, alongside Certificados de Aforro, the way to lend money directly to the Portuguese State. Subscribing means buying retail public debt issued by the IGCP, the agency that manages the State's treasury and debt: the capital is guaranteed and the return is set out in each series' official conditions¹.

While Certificados de Aforro track Euribor and compound, Treasury Certificates have always been the longer-term product with an announced rate: you know today what each year will pay. The series on sale changes from time to time, and that is where 2026's news comes in.

Série 5: the rates on sale since 6 July 2026

Council of Ministers Resolution n.º 141-A/2026, of 3 July, created the Treasury Certificates «Série 5», on sale since 6 July 2026². The term is 10 years and each year's gross rate is fixed and rising¹:

Held to maturity, the series averages 2.71% gross per year. There is no variable component: unlike the old Poupança Valor there is no GDP-growth premium, and unlike Certificados de Aforro nothing depends on Euribor. The rate in the table is the rate you get.

How the interest is paid (and taxed)

Each subscription earns interest once a year, on its anniversary date¹. The interest is paid out to the holder and does not compound: next year's return is again calculated on the subscribed amount, never on accumulated interest. Subscribe €10,000 and you receive €235 gross at the end of the first year, €245 in the second, and so on up to €335 in the tenth.

Each payment is withheld at the flat 28% IRS rate at source (article 71.º of the Portuguese IRS code)³: of the first year's €235 gross, €169.20 reaches your account. The capital repaid at the end is not taxed. Because the withholding is final, you do not need to declare this interest in your IRS return unless you opt for aggregation.

Subscribing, minimums and redemption

Each certificate is worth €1. The minimum subscription is €1,000 and the maximum per holder is €1,000,000¹. You can subscribe through AforroNet (the IGCP's online service), at CTT post-office counters and at participating Espaços Cidadão².

Redemption has two rules worth memorising. First, it is only possible from 1 year after the subscription value date: during the first year the money is locked. Second, redeeming between anniversary dates forfeits the interest accrued since the last annual payment¹. The capital always comes back in full; the cost of leaving mid-year is that year's accrued interest. In practice, the right moment to redeem is on an anniversary date, right after the annual interest is paid.

What happened to Poupança Valor (CTPV)

The Certificados do Tesouro Poupança Valor, the previous series, closed to new subscriptions on 6 July 2026². Existing holders lose nothing: outstanding subscriptions keep their conditions to maturity, including the premium linked to real GDP growth that topped up the rates from year 3, which the IGCP keeps setting quarterly for those subscriptions.

For new savings, the choice within the State's retail debt is now between Série 5 and the Certificados de Aforro Série F.

Treasury Certificates vs Certificados de Aforro

The underlying difference is the kind of risk you accept. Série 5 gives certainty: the rate table is locked and a falling Euribor cannot touch it. Certificados de Aforro follow the market: they pay more when Euribor rises and less when it falls, and the 2.5% cap on the base rate limits the upside. Getting interest paid out yearly (Tesouro) lets you spend or reinvest it; letting it compound (Aforro) puts the interest to work by itself. You can put the two side by side with the savings certificates calculator and our Série 5 calculator.

What they yield: an example

With €10,000 in Série 5 to maturity: gross interest adds up to €2,710 over the 10 years, IRS withheld is €758.80 and €1,951.20 net remains. At the end you get the €10,000 of capital back, for a total of €11,951.20. Redeem after 5 years and gross interest stops at €1,255 (€903.60 net), because the best-paying years are the last ones.

To run the numbers for your case, use the Treasury Certificates calculator: it shows each year's interest, gross and net, and the total at the end. To compare with a bank deposit, the term deposit calculator does the same math on the banks' side, and the compound interest calculator shows what changes when interest stays invested instead of being paid out.