Yes, it's best to report it when you get it. If he's giving it to you monthly, it will cut down on your SSI considerably. However, I don't think they take away $1 for every $1. There is a calculation they use where some of the money is excluded from counting (different calculation for earned and unearned income). But if your countable resources (like savings or checking accounts) go over $2000, that will stop the SSI. SSI is for basic living expenses. People can't give you money, food, clothing, or subsidize your rent without impacting SSI. Your father could pay for items that SSI doesn't cover, like a car payment, insurance, computer equipment, tuition, extras. If you go over the limit, and the SSI stops, I think there is a certain length of time it can be restarted without having to go through the long re-application process. And nothing at all will happen until you get the dollars in your own hand.