CDI Yield Calculator

How CDI-linked returns are calculated

CDI (Certificado de Depósito Interbancário) is the average rate at which Brazilian banks lend to each other overnight. It shadows the Selic policy rate so closely that you can treat it as CDI ≈ Selic − 0.1 pp. With Selic near 15% per year in 2026, CDI sits just under that. When a CDB is advertised at "110% of CDI", it pays 110% of that rate, which works out to roughly 16.5% per year gross. To get the gross final amount you use M = C · (1 + (p · CDI))^(d/252), with 252 business days per year (the standard convention for Brazilian fixed income) and p expressed as a decimal.

Income tax on CDBs follows a regressive table: 22.5% up to 180 days, 20% from 181 to 360, 17.5% from 361 to 720, and 15% past 720 days. The net yield is just net = gross · (1 − IR_rate). So R$ 10,000 at 110% of CDI held for a year yields R$ 1,650 gross, and after the 17.5% bracket you keep R$ 1,361.

Brazilian context in 2026

This calculator lets you line up CDBs, fundos DI, and Tesouro Selic on the same footing. LCI and LCA are exempt from income tax for individuals, but most of them pay under 90% of CDI, and sometimes that tax-free rate still loses to a taxed CDB at 110%. Run both through the net-rate filter before you decide. FGC (deposit insurance) covers up to R$ 250,000 per CPF per institution on CDBs, LCIs and LCAs; Tesouro Selic, on the other hand, carries sovereign risk.

FAQ

Why 252 days and not 365? Brazilian fixed income counts business days (dias úteis) by market convention, since the rates are anchored to the Selic and the Selic only accrues on business days. Over a year, the B3 calendar averages 252 of them.

Does CDI move daily? It does. B3 publishes it every business day, though the variation is tiny. For projections you can treat it as a constant equal to the current Selic minus 0.1 pp and stay accurate enough.

Does the regressive IR reset if I keep money longer? No, it depends only on how long each contribution has been invested. R$ 1,000 deposited 800 days ago is taxed at 15% even if you also added R$ 500 last week, and that newer R$ 500 gets taxed at 22.5% on its own portion.

Is "100% of CDI" a good benchmark? Think of it as the floor for safe fixed income today. Anything below that should be questioned, unless it is IR-exempt like LCI/LCA, and anything well above 110% deserves a hard look at credit risk and FGC coverage.