We are switching our ARMs tied to LIBOR to SOFR at the end of the year. Our existing notes have a fallback statement that says if the current index becomes unavailable, we will select a comparable index and notify the borrower of the change. I search Reg. Z, but I couldn't find any timing or content requirements for a change of index notice. Will this have to follow the normal rate change guidelines, or are changes in index requirements somewhere else?

Unless this gets finalized: https://www.federalregister.gov/doc...tating-the-libor-transition-regulation-z

You are pretty much left with what is currently in Reg Z