My friend got her IRS refund on July 29 for $24 more than the 1040. Do you think it's interest? She already got the Stimulus Check. Haven't seen anyone asking about getting more. Do they figure it from April 15? Gee maybe I should have waited to file mine to get interest. I filed in March and got my refund like in 2 weeks.
The interest that the IRS pays on refunds is taxable income, just like interest from a bank. Your friend will have to report it as interest income on her 2020 tax return. The IRS will send her a Form 1099-INT.