[aianus]

> Unrelated parties are not required to charge interest on loans. (However, interest generally will be imputed on loans between related persons.)

You're never required to charge interest, but in most situations if you receive a below-market loan (from anyone other than a spouse) over $10,000 the IRS will impute interest.

[samstave]

Interesting, I was loaned enough money to buy a house from a family member, and I was required to pay them back with market interest... Thus my comment was from experience - even though I may be wrong?