CDB Investment Guide: Calculate Returns & Choose Best Option
Complete CDB guide: how to calculate returns, compare fixed vs post-fixed rates, taxation rules, and choose the best bank deposit certificate.
The Bank Deposit Certificate (CDB) is one of the main fixed-income options in Brazil, offering higher returns than savings accounts with security guaranteed by the FGC (Credit Guarantee Fund). To invest smartly, it’s essential to understand how to calculate real returns and choose the ideal CDB for your profile.
What is CDB and how it works
CDB is a debt security issued by banks to raise funds. When you buy a CDB, you lend money to the bank and receive interest in return. The investment is protected by the Credit Guarantee Fund (FGC) up to R$ 250,000 per taxpayer ID and per institution.
Types of CDB available
CDBs are divided into three main categories:
- Post-fixed CDB: Returns tied to CDI (usually between 90% to 130% of CDI)
- Pre-fixed CDB: Fixed interest rate defined at the time of investment
- Hybrid CDB: Combines fixed rate + variation of indices like IPCA (inflation index)
Advantages and risks
Main advantages:
- FGC guarantee up to R$ 250,000
- Higher returns than savings accounts
- Various maturity and liquidity options
- Regressive taxation (income tax decreases over time)
Limited risks:
- Institution credit risk (mitigated by FGC)
- Liquidity risk in CDBs without daily liquidity
- Inflation may erode real returns
How to calculate CDB returns
Calculation formula
Post-fixed CDB calculation follows the formula:
Final Value = Initial Value × (1 + CDI × % of CDI)^(days/252)
For pre-fixed CDBs:
Final Value = Initial Value × (1 + annual rate)^(days/360)
Practical example: CDB of R$ 10,000 at 110% of CDI for 1 year (CDI at 12.75% p.a.) = R$ 10,000 × 1.1403 = R$ 11,403 gross
Impact of IOF and income tax
IOF (financial operations tax) applies only in the first 30 days, following a regressive table:
| Days | IOF |
|---|---|
| 1 | 96% |
| 15 | 50% |
| 30 | 3% |
| 31+ | 0% |
Income Tax (IRPF) follows a regressive table:
| Period | IR Rate |
|---|---|
| Up to 180 days | 22.5% |
| 181 to 360 days | 20% |
| 361 to 720 days | 17.5% |
| Over 720 days | 15% |
Use our CDB calculator to simulate net returns considering all taxes.
Pre-fixed vs post-fixed CDB
When to choose each type
Choose pre-fixed CDB when:
- Expecting Selic rate to fall
- Want to guarantee fixed returns
- Deflation or low inflation scenario
Choose post-fixed CDB when:
- Expecting Selic rate to rise
- Prefer protection against economic volatility
- Inflationary scenario
Current comparison: Pre-fixed CDB at 13% p.a. vs post-fixed at 115% of CDI (CDI at 12.75%) = 13% vs 14.66% annual gross return
Economic scenario analysis
In a rising interest rate scenario, post-fixed CDB tends to outperform pre-fixed. In a falling scenario, the opposite occurs.
For long-term investments (2+ years), post-fixed offers greater flexibility to economic changes.
Investment simulation
Examples with different amounts
Investment of R$ 5,000:
| Period | CDB 110% CDI | Gross Return | IR | Net Return |
|---|---|---|---|---|
| 6 months | R$ 5,349 | R$ 349 | R$ 78.53 | R$ 270.47 |
| 1 year | R$ 5,702 | R$ 702 | R$ 140.40 | R$ 561.60 |
| 2 years | R$ 6,451 | R$ 1,451 | R$ 253.93 | R$ 1,197.07 |
Investment of R$ 50,000:
| Period | CDB 120% CDI | Gross Return | IR | Net Return |
|---|---|---|---|---|
| 6 months | R$ 53,825 | R$ 3,825 | R$ 860.63 | R$ 2,964.37 |
| 1 year | R$ 58,230 | R$ 8,230 | R$ 1,646.00 | R$ 6,584.00 |
| 2 years | R$ 67,289 | R$ 17,289 | R$ 3,025.58 | R$ 14,263.42 |
Impact of invested amount
Larger investments don’t change percentage returns, but may provide access to CDBs with better rates offered for high amounts.
Comparison with other investments
Annual net returns (1-year investment):
| Investment | Return | Risk | Liquidity |
|---|---|---|---|
| Savings | 6.17% p.a. | Low | High |
| CDB 100% CDI | 10.20% p.a. | Low | Variable |
| CDB 120% CDI | 12.24% p.a. | Low | Variable |
| Treasury Selic | 10.20% p.a. | Very low | High |
| LCI/LCA | 9.18% p.a.* | Low | Low |
*Tax-exempt
When CDB outperforms other options
CDB is superior to savings in virtually all scenarios. Compared to Treasury Direct, it offers similar returns with FGC guarantee.
Against LCI/LCA (real estate and agribusiness credit letters), CDB can be more advantageous for long-term investments due to regressive taxation.
Tips to choose the best CDB
Selection criteria
Always evaluate:
- CDI percentage offered
- Maturity and grace period
- Financial institution strength
- Liquidity needs
Practical strategies
For conservative profile:
- Prefer large banks (Itaú, Bradesco, Santander)
- CDB with daily liquidity
- Diversify across multiple institutions
For higher returns:
- Consider mid-sized banks with superior rates
- Accept longer terms
- Invest amounts above R$ 30,000 for better rates
For protection:
- Respect the R$ 250,000 limit per bank
- Keep emergency fund separate
- Monitor institution rating
Ideal time to invest
Invest in CDB when:
- Selic rate is above 10% p.a.
- Need security with returns
- Want to diversify fixed income
Use our CDB calculator to compare different scenarios and find the best option for your profile.
Frequently Asked Questions
What is the average return of a CDB today?
Post-fixed CDBs offer between 100% to 130% of CDI, resulting in annual net returns of 10% to 13% for 1-year investments. Pre-fixed CDBs are paying between 12% to 14% per year.
Is CDB better than savings?
Yes, always. With Selic above 8.5%, CDB yields significantly more than savings. A CDB at 100% of CDI currently yields about 65% more than savings.
What’s the minimum amount to invest in CDB?
Most banks accept minimum investment of R$ 1,000 in CDB. Some digital banks allow investments from R$ 100, while large bank CDBs may require R$ 5,000 or more.
Does CDB risk losing money?
No, as long as the FGC limit is respected. CDB is guaranteed up to R$ 250,000 per taxpayer ID and per financial institution. The only real risk is inflation eroding purchasing power.
Can I redeem CDB before maturity?
It depends on the type. CDBs with daily liquidity can be redeemed anytime. Traditional CDBs only allow redemption at maturity, except in special cases provided in the contract.
How is Income Tax charged on CDB?
IR is withheld at source upon redemption, following the regressive table. For investments over 2 years, the rate is 15% on returns. No need to declare in annual tax return if IR was already withheld.
Is it worth investing in small bank CDB?
It can be worth it, as long as the FGC limit of R$ 250,000 is respected. Smaller banks usually pay higher rates (up to 130% of CDI) to attract funds. Always check the institution’s rating and track record.