CDB: What It Is and How It Works in Practice

CDB: What It Is and How It Works in Practice

Have you ever heard someone say they leave their money “earning at the bank” and got curious about how it really works? For many Brazilians, the CDB is the first gateway into the world of fixed-income investments — and for good reason. It’s an accessible product offered by most banks and brokers, and relatively simple to understand. But “simple” doesn’t mean you should invest without knowing what you’re doing.

In this article, we’ll explain what a CDB is, how it works in practice, what its advantages and real risks are, and what you need to consider before applying. The goal is to give you a solid foundation for making more conscious decisions — not a ready-made recipe, because each financial situation is unique.

What is a CDB?

CDB is the acronym for Certificate of Bank Deposit. In simple terms, it’s a security issued by banks to raise money from the public. When you buy a CDB, you are, in practice, lending money to the bank. In return, the bank commits to returning this amount after a determined period, plus interest.

This logic is similar to what the bank uses with you when it grants a loan — except the roles are reversed. Now it’s the bank that borrows, and you receive interest for it.

CDB is a fixed-income product, which means that the remuneration rules are set at the time of application. However, this doesn’t mean the final amount is completely predictable in all cases — as we’ll see later, it depends on the type of CDB contracted.

How does the CDB remunerate the investor?

There are three main types of CDB profitability:

Prefixed CDB

In this modality, the interest rate is set at the time of contracting and does not change. For example, if a bank offers a CDB at 12% per year for two years, you already know exactly how much you’ll receive at the end of the term — regardless of what happens with the economy. The advantage is predictability. The disadvantage: if the basic interest rate rises significantly during the period, you may be “locked” into a rate that fell below the market.

Post-fixed CDB (the most common)

Here, profitability is tied to an indicator, usually the CDI (Interbank Deposit Certificate), which closely follows the Selic rate, set by the Monetary Policy Committee (Copom) of the Central Bank. The offer is usually expressed as a percentage of CDI — such as “100% of CDI” or “110% of CDI”.

Since the Selic and CDI vary over time, the final return of a post-fixed CDB also varies. To find out the current Selic rate, consult directly on the Central Bank of Brazil website. Never use a number mentioned in articles or videos as reference without verifying the date of the information.

Hybrid CDB (IPCA+)

Combines a prefixed rate with the variation of IPCA, Brazil’s official inflation index, measured by IBGE. For example: “IPCA + 6% per year”. This format ensures that your money, in theory, preserves purchasing power and still earns something above inflation. It’s an interesting option for medium and long-term objectives, but requires attention to the maturity date.

Who can issue and where to buy?

CDB can only be issued by financial institutions authorized by the Central Bank — commercial banks, investment banks, finance companies, among others. This is important: be suspicious of any product called a “CDB” that is not issued by a regulated institution.

To buy, you have a few options:

1. Directly on the app or internet banking of your bank.
2. Through a brokerage firm or investment platform — where it’s possible to compare CDBs from different issuers in one place.
3. Some brokers allow investments with quite accessible initial amounts, sometimes starting at R$ 1.00 (the minimum amount varies according to the product and platform).

Taxation: how much tax do you pay?

CDB has Income Tax (IR) charged on earnings, following the regressive table of the Federal Revenue Service, which rewards those who keep their money invested for longer:

Tax is withheld at the source automatically on redemption — you don’t need to do anything manually. But attention: IR is charged only on earnings, not on the principal amount invested.

In addition to IR, applications with a period of less than 30 days are also subject to IOF (Tax on Financial Operations), whose rate decreases progressively until it reaches zero on the 30th day. In practice, this means that redeeming a CDB in less than 30 days can be quite disadvantageous.

To always verify current rates, consult the official website of the Federal Revenue Service.

Advantages and risks of CDB

Understanding both sides is fundamental for any conscious financial decision.

Advantages

• Protection by the FGC: CDB has coverage by the Credit Guarantee Fund (FGC), which guarantees up to R$ 250,000 per CPF per financial institution, with a global cap of R$ 1 million per CPF every four years. This offers an important layer of security in case of bank failure.
• Accessibility: it’s one of the easiest fixed-income products to find and apply for, with low minimum amounts on many platforms.
• Variety: it’s possible to find CDBs with different terms, profitability modalities, and issuers, which allows for some customization.
• Liquidity in some cases: many CDBs offer daily liquidity, meaning you can redeem whenever you want — but this is generally accompanied by lower rates.

Risks and disadvantages

• Credit risk: if the issuing bank fails, you depend on the FGC to recover the amount. The FGC reimbursement process can take some time. Smaller banks usually offer more attractive rates precisely because the risk is perceived as higher.
• Liquidity risk: many CDBs do not have daily liquidity. Redeeming before maturity may not be possible — or may result in loss of profitability. Always read the product conditions before applying.
• Taxation: unlike products such as LCI and LCA (which have IR exemption for individuals), CDB is always taxed. Over shorter time horizons, this can significantly reduce net earnings.
• Inflation: a post-fixed CDB tied to CDI can earn below inflation in specific scenarios. There’s no guarantee that real return (above inflation) will always be positive.

CDB with daily liquidity vs. CDB with fixed maturity: which to choose?

This is a very common doubt. The answer depends on your objective:

• If you want to build or supplement an emergency fund, a CDB with daily liquidity makes sense — you need quick access to the money. In this case, also compare with other daily liquidity options available in the market.
• If you have a medium or long-term objective (a trip, a property, retirement) and can leave the money idle for longer, a CDB with fixed maturity tends to offer better rates — and the regressive IR table benefits those who wait longer.

A practical tip: never put money that might be needed soon and money that can stay invested for years in the same basket. Organize your investments by objectives and terms.

If you’re thinking about alternatives for larger goals, such as buying a property, it’s also worth understanding how other modalities work, such as property consortiums, which have a completely different logic from CDB and may be complementary depending on your planning.

How to start investing in CDB

1. Organize your finances first. Investing with expensive debts (such as credit cards or overdrafts) rarely pays off. If that’s your case, prioritize negotiating overdue debts before investing.
2. Open an account at a brokerage or use your bank’s app. Brokers usually offer more options to compare.
3. Compare rates and terms. Don’t accept the first CDB that appears. Compare the CDI percentage, the term, liquidity, and the issuer.
4. Verify that the issuer is authorized by the Central Bank. The BC website has a list of authorized institutions.
5. Check FGC coverage. Know what the current limit is and how it works at fgc.org.br.
6. Read the product conditions carefully. Minimum term, conditions for early redemption, and taxation should be clear before confirming the application.
7. Diversify. Don’t concentrate all your money in a single CDB or a single issuing bank.

Conclusion

CDB is a relevant fixed-income instrument, accessible and with well-defined rules — a good option for those starting to organize investments or seeking alternatives to savings accounts. But like any investment, it has risks, tax costs, and conditions that need to be understood before applying.

The most important thing is that you make decisions based on real and up-to-date information: always consult official sources (Central Bank, Federal Revenue Service, FGC) before acting, and don’t take any number as absolute truth unless you’ve verified it yourself.

Investing well begins with education — and you’ve already taken an important step by seeking to understand the product before putting your money into it.

> Important note: This article is exclusively educational in nature and does not constitute investment recommendation. Each financial situation is unique. For investment decisions appropriate to your profile and objectives, consult a professional or investment advisor properly registered with the Securities and Exchange Commission (CVM).