Treasury and Census are working together and committed to helping governments comply with the American Rescue Plan Act and expect further guidance to be forthcoming regarding revenue loss calculations and other related provisions of the Act. Treasury is planning to update their FAQs regularly.  This will be their main way of providing updates before the interim rule is finalized.  A few basic FAQs can be found at  https://home.treasury.gov/system/files/136/SLFRPFAQ.pdf.