Most W-9 forms do not need to be signed. So unless it relates to a financial transaction, FATCA or a u201cB noticeu201d the minor can prthe form without a signature.W-9 forms related to the following financial transactions are required to be signed.Interest accounts u2022 bank interest (1099-INT)Dividend accounts (1099-DIV)Barter exchange accounts (1099-B)Broker accounts (1099-B)Original issue discounts (1099-OID)Patronage dividends (1099-PATR)Real estate transactions (1099-S)