The state -- probably its Department of Revenue, which usually is the administrator of unclaimed property -- has the answer. If she has waited months without asking, she must not be too concerned about paying taxes and you should just put it all under "Other Income." Maybe file an amended return later if her curiosity gets the best of her. Right now you're asking blind men to describe an elephant. What I see is dividends after his death -- so income in respect of a decedent -- and loss on stock sale. But then there's the issue of whether the statute has expired. It doesn't start running for his estate 1041, until the return is filed.