A friend of mine in the U.S.A. works for an employer who, we believe, improperly withheld FICA (should have been exempt: they are a student at the same university that they work) due to an administrative error.
We believe the FICA will be refunded, but, could one request interest be paid in addition to the original sum because it was an error on their part? If so, how would the interest rate be calculated?