CDB Multi-Scenario Calculator

How CDB yields work

A CDB (Certificado de Depósito Bancário) is a bank debt note: you lend money to the bank and it returns principal plus interest. Three flavors exist. Post-fixed (the most common) pays a percentage of CDI — e.g. "110% of CDI". Pre-fixed locks a fixed annual rate for the entire term. Hybrid pays IPCA + fixed %, protecting purchasing power. The gross-yield formula in business days is M = C · (1 + i)^(d/252), where i is the effective annual rate.

IR follows the regressive table: 22.5% up to 180 days, 20% 181-360, 17.5% 361-720, 15% above 720. Example: R$ 10,000 in a CDB at 110% of CDI for 1 year (CDI = 15%) yields R$ 1,650 gross; IR at 17.5% is R$ 289 → R$ 1,361 net. Liquidity varies a lot: some CDBs are D+0 (same-day withdrawal), others D+1, D+30, D+360, or only at maturity.

Brazilian context in 2026

With Selic at 15%, the daily-liquidity CDB market hovers at 100-105% of CDI; smaller or less-known banks push to 115-120% to compensate for higher credit risk. FGC covers up to R$ 250,000 per CPF per financial conglomerate, so spreading larger amounts across institutions is standard practice. Use cases: emergency reserve (daily-liquidity CDB), 1-3 year goals (pre or post-fixed), and inflation protection (IPCA+). Online brokers display the rate menu side by side — always compare net rates, not gross.

FAQ

Is a CDB at 120% of CDI a scam? Not necessarily — small banks pay more to attract deposits. As long as the issuer is FGC-protected and your total exposure to that conglomerate stays under R$ 250,000 (including interest), the risk is bounded.

Can I withdraw before maturity? Only if the CDB has explicit early liquidity. Otherwise you wait for vencimento, or the broker may offer a secondary-market sale at a discount.

What is IOF on a CDB? IOF applies only in the first 30 days, on a sliding scale (96% on day 1 down to 0% on day 30). After 30 days there is no IOF — only IR on withdrawal.

Does the bank tax me directly? No — IR is withheld at source (na fonte) by the custodian when you redeem. The net amount that hits your account is already after IR.