Hyphens, En Dashes, Em Dashes

Q. Does CMOS have an official position on hyphenating “the then” when used to indicate something or someone’s former status?

A. Since then is just an adjective like any other adjective, there’s no need for a hyphen.

• the current secretary of state
• the previous secretary of state
• the then secretary of state

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]