It is the right to recover wrongfully paid amounts, provided in CC arts. 876 to 883 and, for consumers, in CDC art. 42, sole paragraph.
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Calculate the amount to be refunded for wrongful charges, single or double, with monetary correction and interest.
Restitution of wrongful charges (repetição de indébito) is the technical name for the right to recover what you paid without owing it, a fee charged twice, an overcharge, an undue tax. The point that raises the most doubt is how much comes back: in consumer relations, the CDC (art. 42, sole paragraph) provides a double refund when the wrongful charge does not stem from a justifiable mistake; in civil relations, the refund is simple, except for judicial collection of an already-paid debt (CC art. 940); for federal taxes, the refund is always simple, but updated exclusively by the SELIC rate (Law 9.250/1995, art. 39, §4). This calculator applies the civil regime consolidated by the STJ for consumer and civil relations, or SELIC for tax refunds, lets you enter more than one charge with different dates (the consumer double depends on each charge's date), and simulates the double amount. As an estimate, the characterization of bad faith and the applicability of the double refund should be confirmed with an attorney.
A single refund repays what was paid, corrected and with interest. A double refund, exclusive to consumer relations (and the specific CC art. 940 case in civil relations), adds an amount equal to the wrongful charge, in practice, you get twice what you overpaid. But the consumer double is not automatic: under CDC art. 42, sole paragraph, it requires that the wrongful charge did not stem from a "justifiable mistake."
The STJ modulated this understanding in EAREsp 676.608/RS (judged 10/21/2020, published 03/30/2021, jointly with EREsp 1.413.542/RS): for charges made from the publication of the thesis onward, the double applies whenever the wrongful charge is unjustified, regardless of proof of bad faith; for charges before that date, the double is only owed with proven bad faith. In civil relations (outside the CDC) and federal taxes, there is no double for mere mistake: restitution is always simple.
Example 1, post-modulation consumer relation: a carrier wrongfully charges R$ 500 for a service that was not contracted in 2023. With the double applying automatically, the restitution base becomes R$ 1,000 (the amount paid plus the double addition), and monetary correction and interest accrue on that up to the target date.
Example 2, civil relation with no bad faith: the same R$ 500 wrongfully paid between private parties, outside the CDC, is refunded simply: R$ 500 corrected and with interest, no double. Example 3, an overpaid federal tax: the refund is also simple, but the update uses the SELIC rate from the payment month through the month before restitution, without splitting correction and interest. The tool lets you enter each charge with its own date, which matters when a case has amounts both before and after 03/30/2021.
The window to seek restitution is usually 5 years, whether in a consumer relation (CDC, art. 27, for reparation) or civil one (CC, art. 206, §5), and also for taxes (CTN, art. 168, I). Counting from the wrongful payment is the practical rule, after that period, the right to claim prescribes.
Correction follows the nature. In civil and consumer relations, the STJ's general civil regime applies (full SELIC until 08/29/2024 and, after that, IPCA + Legal Rate, under Law 14.905/2024). For federal tax refunds, only the SELIC rate applies, with no separate interest (Law 9.250/1995, art. 39, §4). That is why choosing the nature changes both the double and the update index.
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src="https://jkit.tools/embed/en-US/undue-payment-refund-calculator"
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></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
It is the right to recover wrongfully paid amounts, provided in CC arts. 876 to 883 and, for consumers, in CDC art. 42, sole paragraph.
⚠️ Educational estimate. Confirm applicability of double refund with attorney before filing.
Charge 1: R$ 920,62
CDC art. 42, sole paragraph; CC arts. 876-883 and 940; STJ EAREsp 676.608/RS (modulated 03/30/2021); Law 9.250/1995, art. 39, §4 (federal taxes).