Fixed or Variable Income: How to Choose the Best Option
You’ve finally decided to invest, but when you open any platform you’re faced with an avalanche of acronyms and categories: CDB, Tesouro Direto, LCI, stocks, REITs, ETFs… The first major division you need to understand before anything else is between fixed income and variable income. This choice isn’t trivial and goes far beyond “which yields more”. It relates to your profile, your life stage, and how much uncertainty you can tolerate without losing sleep.
The good news is that there’s no universal right answer. The bad news — which is actually a valuable lesson — is that every investment carries some type of risk, even those called “safe”. What changes is the nature and intensity of that risk. Understanding this is the starting point for making more conscious decisions aligned with your goals.
In this article, we’ll break down the main characteristics of each category, honestly compare advantages and disadvantages, and present the factors you should consider when building or reviewing your portfolio. No magic formula, no promises of quick enrichment — just solid financial education.
What Is Fixed Income?
Fixed income is the category of investments where remuneration rules are defined at the time of application. This doesn’t mean the return is always a fixed, immutable number, but rather that the calculation logic is known from the start.
There are three major types of fixed income remuneration:
- Pre-fixed: the interest rate is defined at the time of contracting (e.g., “12% per year”). You know exactly how much you’ll receive if you hold the security until maturity.
- Post-fixed: the return tracks an index, usually the CDI (Interbank Certificate of Deposit) or the Selic rate. The final value is only known at redemption.
- Hybrid (IPCA+): combines a fixed rate with inflation variation measured by IPCA. It protects purchasing power and still guarantees real gains above inflation.
Common examples of fixed income products
- Tesouro Direto (federal public securities issued by the government, available at tesouro.fazenda.gov.br)
- CDB (Bank Certificate of Deposit, issued by banks)
- LCI and LCA (Real Estate Credit Letters and Agribusiness Credit Letters, tax-exempt for individuals)
- CRI and CRA (Receivables Certificates, also tax-exempt for individuals)
- Debentures (securities issued by private companies)
FGC Protection
Much of the banking fixed income products benefit from Credit Guarantor Fund (FGC) protection. Currently, the FGC covers up to R$ 250,000 per CPF per financial institution, with a global ceiling of R$ 1 million per CPF every four years. Check updated rules at fgc.org.br. Tesouro Direto public securities don’t need FGC — they have the guarantee of the federal government itself.
What Is Variable Income?
In variable income, there’s no way to predict the return at the time of application. The investment value fluctuates according to the market, potentially rising, falling, or even reaching zero in extreme cases. The risk is higher, but the potential for returns over time can also be superior — with no guarantee that it will materialize.
Common examples of variable income products
- Stocks: participation in the capital of companies listed on B3
- REITs (Real Estate Investment Funds): fund shares that invest in real estate or real estate securities
- ETFs (Exchange Traded Funds): funds traded on exchanges that replicate indexes like Ibovespa or the S&P 500
- BDRs (Brazilian Depositary Receipts): receipts for shares of foreign companies traded on B3
- Cryptoassets: digital assets with high volatility and regulation still being consolidated in Brazil
B3 (b3.com.br) is the main Brazilian stock exchange and concentrates trading of most of these assets in the country.
Taxation: An Important Difference
Taxation directly impacts the net return on your investments. See how it works in general terms — and always check current rates at the Federal Revenue Service:
Taxable fixed income (CDB, Tesouro Direto, etc.)
Income tax applies to earnings and follows a decreasing scale: the longer you hold the investment, the lower the rate. Current brackets (verify updates at Federal Revenue) work like this:
- Up to 180 days: highest rate
- 181 to 360 days: intermediate rate
- 361 to 720 days: lower rate
- Over 720 days: lowest rate
Tax is withheld at the source by the financial institution at redemption.
Tax-exempt fixed income
LCI, LCA, CRI and CRA are exempt from income tax for individuals. This can make them more attractive in terms of net returns, but it’s important to always compare the gross rate with taxable product rates to see which yields more after tax.
Variable income
On stocks, the income tax rate is 15% on profit for common operations (swing trade) and 20% for day trading (buy and sell on the same day). There’s income tax exemption for stock sales that don’t exceed R$ 20,000 in a month — a rule that applies only to the spot equity market. The investor is responsible for calculating and collecting tax via DARF. REITs have specific taxation: distributions of earnings to shareholders are exempt from income tax (for individuals in funds meeting legal criteria), but capital gains on share sales are taxed at 20%.
Risk: The Factor Nobody Likes to Talk About
Many people associate “risk” only with variable income. But fixed income also has its risks — they’re different, not absent.
| Type of Risk | Fixed Income | Variable Income |
|---|---|---|
| Credit (issuer default) | Yes (except National Treasury) | Partially (company bankruptcy) |
| Market (price fluctuation) | Low (if held to maturity) | High |
| Liquidity (difficulty withdrawing) | Varies by product | Varies by asset |
| Inflation (loss of purchasing power) | Exists in pre-fixed | Exists, but with potential to exceed |
| Emotional volatility | Low | High |
A little-discussed point: pre-fixed securities fluctuate in price on the secondary market before maturity. If you need to sell a Pre-fixed Tesouro early at a time of rising interest rates, you may receive less than you invested. This is called mark-to-market and it’s a reality every fixed income investor needs to know.
How to Choose? The Four Essential Factors
There’s no single formula, but there are fundamental questions that guide the decision:
1. What is your objective?
- Emergency fund: needs immediate liquidity and safety. Fixed income products with daily liquidity (like Tesouro Selic) are most appropriate for this purpose.
- Short-term goal (up to 2 years): fixed income tends to be more appropriate, as it avoids exposure to market volatility.
- Long-term goal (5 years or more): variable income can be part of the portfolio, as longer horizons have historically diluted the effects of volatility — but with no guarantee of returns.
2. What is your risk profile?
Investment platforms and brokerages are required by CVM to apply Suitability — a questionnaire that assesses your profile (conservative, moderate, or aggressive). This doesn’t determine what you should do, but it’s a starting point for financial self-knowledge.
3. What is your current financial situation?
Before any investment, it’s recommended to have an emergency reserve equivalent to at least 3 to 6 months of essential expenses. Investing without a reserve can force you to withdraw applications at the worst moment. If you’re still building that base, earning extra money in spare hours can be a valid complementary strategy while organizing your finances.
4. Do you have time and willingness to monitor?
Variable income requires more attention, study, and emotional tolerance. In moments of sharp market declines — and they always happen — it’s necessary not to make impulsive decisions. If you don’t have time or interest in monitoring the market, simpler fixed income products may be more suited to your lifestyle.
Diversification: The Most Honest Strategy
The vast majority of financial educators and experts converge on one point: diversifying is the most consistent way to balance risk and return over time. This doesn’t eliminate risks, but distributes exposure to different types of risk.
In practice, a diversified portfolio can combine:
- A portion in highly liquid fixed income (for emergencies and short-term goals)
- A portion in medium/long-term fixed income (for specific goals with defined timeline)
- A portion in variable income (for long-term goals, with tolerance for volatility)
The ideal proportion between these categories depends on each person and each life stage. There’s no “correct” division valid for everyone.
Conclusion: Education Before Any Decision
The choice between fixed and variable income isn’t a battle where one side wins and the other loses. They are different tools for different objectives. The most common mistake isn’t choosing “the wrong investment” — it’s investing without understanding what you’re buying.
Before applying any amount, research from official sources: the Central Bank publishes data on interest rates; Tesouro Direto details each public security available; CVM regulates the capital market and offers free educational materials. Quality information is the best investment you can make before any other.
And remember: just as carefully evaluating your finances before investing is fundamental, carefully evaluating your consumption and income decisions is also part of the set — something we cover in more detail in our content on financing or consortium: which to choose in 2026?.
> Educational Note: This article is exclusively educational and informational in purpose. It does not constitute a recommendation, offer, or investment suggestion. Market conditions, rates, tax rates, and rules may change; always consult official sources for updated information. For investment decisions appropriate to your profile and financial situation, consult a certified professional or investment advisor properly registered with the Securities Commission (CVM).
