Did you previously receive a 2019 Federal tax refund? If so, this may be an interest payment. You may get a Form 1099-INT in January 2021, and will need to report the $16 in interest on next year's tax return. See this article at the IRS website:
https://www.irs.gov/newsroom/13-point-9-million-americans-to-receive-irs-tax-refund-interest-taxable...
