The IRS has released (Rev. Rul. 2020-09) the Applicable Federal Rates under Sec. 1274(d) of the Internal Revenue Code. These rates are used for various tax purposes, including minimum rates for loans.
There are rates for "short-term," "mid-term," and "long-term" instruments. Short-term covers demand loans and instruments extending up to three years. Mid-term covers loans cover instruments of over three years up to nine years. Long-term covers instruments with maturities longer than nine years.
Historical AFRs are available here.