Answers to this question link several other Q&As on the theme that if someone accidentally sends you a pile of money, you need to give it back. Fair enough.

If someone sends me $100k accidentally, and a month later asks for it back, how much do I owe them? More specifically, if I hold it in an interest-bearing account, but return it promptly on demand, who keeps the interest?

(Assume for simplification that I had no way to notify the payer in a more timely way, but return the original amount promptly on demand).

Asking about US law, but other jurisdictions might be interesting too.

1 Answer 1


What you describe is unjust enrichment.

The elements of unjust enrichment are: (1) an enrichment; (2) a corresponding deprivation; and (3) the absence of a juristic reason for the enrichment.

if I hold it in an interest-bearing account, but return it promptly on demand, who keeps the interest

The interest you would make easily falls within the above analysis and would be paid back to the rightful holder of the money. This is not a windfall for them nor any unfair deprivation to you. You wouldn't have had that interest if not for the erroneous $100k transfer, and they probably would have had that interest instead.

In the case where you did not actually deposit the money, but dragged the process out through court instead of just returning the money, you would owe court-calcluated pre-judgment interest, starting from the date the cause of action arose (the date you got the money).

Courts will not let this result in double-recovery, so you will not have to pay back two types of interest: only what you actually made (part of the unjust enrichment remedy), or the court-computed pre-judgment interest, whichever is higher.

  • 2
    Does this mean that an accidental recipient of money who does not deposit it in an interest bearing account must pay interest, despite not wanting to have received the money in the first place?
    – Someone
    Commented Feb 23 at 6:15
  • 4
    @Someone I'd assume this hinges on whether you have actively and demonstratively tried to remedy the situation and return the money ASAP. In OP's example the opposite has happened.
    – Roland
    Commented Feb 23 at 6:52
  • 3
    @Someone In practice there is also the restriction that the amount of interest must be significant enough to justify the hassle. In OPs example of 100k $ for 1 month the interest would be a few hundred dollars, that is probably around the minimum where anyone would bother to try to claim interest.
    – quarague
    Commented Feb 23 at 8:39

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