I'm looking for guidance on modern-day US tax law.
Trying to google various permutations of "income", "tax", "anonymous", and "gift" gets me a lot of information on the taxes a gift giver needs to pay on a gift, or how to anonymously donate to a charitable organization for an income tax deduction.
What I really need to know is whether or not an individual who receives a very substantial financial gift must report it as income or otherwise pay taxes on it. My story has an anonymous benefactor paying off the outstanding balance on my main character's mortgage, a sum well over $100,000. I'd like to set it up where the benefactor overpays by an amount sufficient to also cover any taxes the main character would incur as a result of the gift.
I'm assuming that if the benefactor found some way to pay the gift tax, the IRS wouldn't also pursue the recipient for additional taxes, since Uncle Sam has already taken his cut on the transaction. However, if the benefactor wishes to remain anonymous, does the IRS then pursue the recipient to make sure they get their cut?