[1]: https://en.wikipedia.org/wiki/Bounty_(reward)

> The IRS Whistleblower Office pays monetary awards to eligible individuals whose information is used by the IRS. The award percentage depends on several factors, but generally falls between 15 and 30 percent of the proceeds collected and attributable to the whistleblower's information. Awards can only be issued once a final determination can be made, and as such, award payments cannot be made until the taxpayer has exhausted all appeal rights and the taxpayer no longer can file a claim for refund or otherwise seek to recover the proceeds from the government.

Know someone with $100k of unpaid taxes? That's a $15k - $30k payout.

(edit) The report for 2020 - https://www.irs.gov/pub/irs-pdf/p5241.pdf

In 2020 they had 593 claims, 169 awards. They collected $472M and paid out $86M (18.3%).

This is down from 2018 where $1.4B was collected, and $312M payouts where given.

When you said whistle blower, I initially thought of workplace whistle blower.