It isn't your possession, so no. Your aunt will be until she dies. The thing to grasp here is that it's not the income that's taxed, it's the wealth. Like your house or car (if you live in a state with auto property taxes). Not like your paycheck.

Some companies actually value their brand reputation on their books in money. Would you tax that ? Would you tax people’s good reputation and good looks, or working arms and legs ? I owe you’s are even more commonly held as assets on people’s and company books. Would you tax flying kisses ? Would you tax well wishes, friendships ?