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Savings Certificates and IRS: how the interest is taxed in Portugal

Interest on Portuguese Savings Certificates pays IRS at a 28% rate, withheld at source. Here is when you actually have to declare it and when aggregation can save you tax.

4 min readReviewed By Thorben Rasmus IdelReviewed by Nahar Geva

TL;DR

Interest on Savings Certificates and Treasury Certificates is capital income (Categoria E) and pays IRS at a flat 28% rate, withheld at source by the IGCP. Because the withholding is final, you receive the interest net and, as a rule, have nothing to declare. You can opt for aggregation and pay the progressive rates, which only pays off if your marginal IRS rate is below 28%; in that case you report the interest in Anexo E and must aggregate all your Categoria E income.

Is interest on Savings Certificates taxed?

Yes. Savings Certificates (and Treasury Certificates) are Portuguese State savings products, but the interest they earn is not tax-free: it is capital income in Categoria E of IRS and pays a 28% rate1. If you first want to understand how the product works and how the interest grows, see the article on what Savings Certificates are. This guide focuses on the tax side: how much IRS you pay, when you have to declare it and when aggregation can pay off.

The 28% rate is withheld at source

The 28% rate is a final withholding rate (Art. 71 of the IRS Code)1: the tax is withheld at source by the IGCP, the agency that manages the certificates, at the moment the interest is paid or capitalised. In other words, you receive the interest already net of tax, with nothing further to do.

That is why the Savings Certificates calculator shows the net value as its main result: what actually lands in your account after the 28%. What compounds quarter after quarter is the net interest too.

Do I have to declare Savings Certificates on IRS?

As a rule, no. Because the 28% withholding is final, the tax is settled at that moment and there is nothing left to reconcile. Interest on Savings Certificates does not need to be declared in your Modelo 3 return.

The only situation where you include it in the return is when you decide to opt for aggregation. Then, and only then, you report the interest in Anexo E (capital income).

The aggregation option: when it pays off

Instead of the flat 28% rate, you can opt for aggregation: add the interest to your other income and pay the progressive IRS rates1. The 28% already withheld is not lost, it is deducted from the final tax.

Aggregation only pays off if your marginal IRS rate is below 28%, which usually happens at lower incomes. If your marginal rate is 28% or higher, you are better off with the flat rate and aggregation is not worth it. To see which bracket you are in, read how IRS is calculated.

Aggregate one, aggregate all

There is a rule that is easy to forget: if you opt to aggregate the interest on Savings Certificates, you are required to aggregate all income of the same category (Art. 22 of the IRS Code)2. That includes term-deposit interest, Treasury Certificates and other capital income for the year.

You cannot choose to aggregate only the interest that suits you and leave the rest at the 28% rate. The option is "all or nothing" within Categoria E, and it should be weighed against your whole set of capital income, not a single product in isolation.

Treasury Certificates and term deposits: the same regime

The taxation described here is not exclusive to Savings Certificates. Treasury Certificates follow exactly the same treatment: 28% withheld at source on the interest3. And the interest on bank term deposits is also capital income taxed at 28%. That is why, when deciding on aggregation, you have to look at all of this income together.

A worked example

Suppose your Savings Certificates earned 500 EUR of interest in a year.

  • At the flat 28% rate, the IGCP withholds 140 EUR and you receive 360 EUR net. You have nothing to declare.
  • If you opted for aggregation and your marginal IRS rate were 23%, the tax on that interest would be 115 EUR instead of 140 EUR, a saving of 25 EUR. You would report it in Anexo E and the 140 EUR already withheld would be deducted from the final tax.

Note that, by aggregating, you would also have to add the interest from any term deposits and Treasury Certificates for the same year. You can estimate the net interest on your certificates with the Savings Certificates calculator.

The takeaway

Interest on Savings Certificates and Treasury Certificates pays 28% IRS, withheld at source, so as a rule you have nothing to declare. Aggregation is an option that only pays off if your marginal rate is below 28%, requires you to aggregate all Categoria E income, and is reported in Anexo E. Work out the net interest with the Savings Certificates calculator and, if in doubt about the return, check with the tax authority or an accountant.

Common mistakes

  • Assuming you always have to declare Savings Certificates

    Because the 28% tax is withheld at source as a final tax, you receive the interest net and, as a rule, do not need to declare anything. Declaring is only necessary if you opt for aggregation.

  • Aggregating only the interest that suits you

    If you opt to aggregate the interest on Savings Certificates, you are required to aggregate all income of the same category (Categoria E): term-deposit interest, Treasury Certificates and other capital income. You cannot choose to aggregate some and leave others at the 28% rate.

Frequently asked questions

Is interest on Savings Certificates taxed in Portugal?
Yes. The interest is capital income (Categoria E) and pays IRS at a flat 28% rate (Art. 71 of the IRS Code). The tax is withheld at source by the IGCP, so you receive the interest already net of tax.
Do I have to declare Savings Certificates on IRS?
As a rule, no. Because the 28% withholding is final, the tax is settled and you have nothing to declare. You only need to include the interest in your return if you opt for aggregation, and then you report it in Anexo E.
When does aggregation pay off for Savings Certificates interest?
Aggregation (adding the interest to your other income and paying the progressive IRS rates) only pays off if your marginal IRS rate is below 28%, which tends to happen at lower incomes. If your marginal rate is 28% or higher, the flat rate is better.
Are Treasury Certificates taxed the same way?
Yes. Interest on Treasury Certificates is also capital income and pays 28% withheld at source. The same regime applies to term-deposit interest.
What happens if I aggregate the interest?
When you opt for aggregation, the interest is added to your other income and taxed at the progressive rates; the 28% already withheld is deducted from the final tax. The option requires you to aggregate all Categoria E income.

Related reading & calculators

Sources

  1. 1.Personal Income Tax Code (CIRS), Art. 71 (final withholding rates and the aggregation option) — Autoridade Tributária e Aduaneira · retrieved 14 Jun 2026
  2. 2.Personal Income Tax Code (CIRS), Art. 22 (aggregation of income) — Autoridade Tributária e Aduaneira · retrieved 14 Jun 2026
  3. 3.Savings Certificates and Treasury Certificates — IGCP, the Portuguese public debt agency · retrieved 14 Jun 2026
  4. 4.Todos Contam, financial education portal — Banco de Portugal · retrieved 14 Jun 2026

Author / Reviewed by

Author

Thorben Rasmus Idel

Co-founder & writer

Co-founder of Calculadora Capital and the writer behind the methodology on every calculator and article. An entrepreneur and active investor, Thorben founded Idel Versandhandel GmbH, an international trading company operating across 16 countries, and invests across stocks, ETFs and cryptocurrency. He writes the methodology and verifies the math behind each page, drawing on hands-on business and investing experience to keep the tools and explanations grounded in how money, markets and taxes actually work for everyday people in Portugal.

Reviewed by

Nahar Geva

Co-founder & reviewer

Co-founder of Calculadora Capital and the independent reviewer behind every calculator and article. An entrepreneur and active investor, Nahar brings a data- and product-driven mindset together with hands-on experience in the markets — investing across stocks and ETFs as well as cryptocurrency and other digital assets, alongside broader personal finance and real estate. On each page Nahar reviews the methodology and double-checks the math and figures, pressure-testing how the tools and explanations hold up against the way money, markets and taxes actually work for everyday investors.

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