Nonbusiness creditors may deduct bad debts when they become totally worthless (i.e. there is no chance of its repayment). The proper year for the deduction can generally be established by showing that an insolvent debtor has not timely serviced a debt and has either refused to pay any part of the debt in the future, gone through bankruptcy, or disappeared. Thus, if you have loaned money to a friend or family member that you are unable to collect, you may have a bad debt that is deductible on your personal income tax return.
The fact that the debtor is a family member or other related interest does not preclude you from taking a bad debt deduction, provided that the debt was bona fide and that worthlessness has been established. A direct or indirect transfer of money between family members may create a bona fide debt eligible for the bad debt deduction. However, these transactions are closely scrutinized to determine whether the transfer is a bona fide debt or a gift.
Read the full Bad-Debt-Deduction article.