Yes, but you don't get the reward until the IRS collects from the cheater. There are two different programs depending on the amount of money involved. For cases involving less than $2 million or individual taxpayers with gross incomes of less than $200,000, the maximum amount that can be awarded is 15% of the amount collected. These awards are discretionary and the informant cannot dispute what the IRS decides. If the case involves someone whose gross income exceeds $200,000 or the amount involved is over $2 million, the IRS will pay 15% to 30% of the amount collected.
Typically, you will never know what action, if any, is taken on your tip, but if you want to try it, submit IRS Form 211.