Yes. Charging interest on a loan is important because it sets up the agreement as something other than a gift or a handout. Interest can also make up for differences in inflation between the start and the end of the loan. The interest rate for a personal loan to give should be determined by the length of repayment and any national government approved interest rates for family loans. The annual limit for tax-free gifts to family members in Australia is $14000, so especially when you loan is beyond that, should you charge interest.