Mindful credit-card spending

Purchase & card

Purchase price (R$)

Instalments

Financing rate (% monthly)

First payment

Investment start

CDB & taxation

Investment modelReferenceCDI participationCDI: —% a.a. · —Maturity (months)Daily-liquidity CDB. Partial withdrawals deduct tax on the income portion. Net proceeds are reinvested at maturity.

Card benefits

BenefitCashback (%)

Assumptions & rules

The purchase amount is invested in one CDB before the first payment. Returns are gross; regressive income tax and IOF before 30 days apply only to the withdrawn profit portion. The final remaining balance is liquidated too. Maturities restart the tax holding period. Rates stay constant; returns are not guaranteed.

Price instalments, first due today or next month. Cashback is deducted once; miles are a quantity, without a cash value. Annual card fees, cash-payment discounts, credit IOF and unreported charges are excluded.

Official income-tax table

How to simulate instalments with the purchase amount invested

Compare an instalment purchase while accounting for the return on money set aside and the benefits of your card. The simulator tracks the investment balance and the withdrawals used to pay each instalment. Form values are editable examples, not credit offers or current market rates.

Step by step

Enter the purchase price, number of instalments and monthly financing rate. Use zero for interest-free instalments.
Choose CDB at 100% CDI (adjustable), a custom gross rate or your own net rate. Set the start date and maturity.
Select cashback, points and miles, or no benefit. For points, enter the card’s dollar conversion rate and points-to-miles ratio.
Compare total payments, investment income, extra cash required and effective purchase cost. Review the monthly schedule to understand each withdrawal.

Calculation method

The initial investment equals the purchase price. Each month the model applies the estimated return and withdraws the payment. When the balance cannot cover a payment, the difference is recorded as extra cash required. Effective cost is total payments less investment income and cashback, where applicable. Points and miles are shown as quantities without assigning them a cash value.

Assumptions and limitations

Daily-liquidity CDB with constant rates and automatic income tax/IOF per partial withdrawal, including liquidation of the remaining balance. Excludes annual card fees, credit IOF, unreported charges and cash discounts. Remaining cash is not deducted twice.

Common questions

Can I simulate an interest-free purchase?

Yes. Set monthly financing interest to 0%. The schedule will use that assumption.

Do miles reduce the cost in cash?

Not in this simulator. Miles are shown as a quantity because their value depends on the programme and how you redeem them.