Q. Are there compounds that are always hyphenated, such as “up-to-date” or “step-by-step,” or are these only hyphenated when modifying another word, as in “up-to-date rules” or “step-by-step procedures”? My company is writing “We’ll walk you through it step by step,” and I thought that it should be “We’ll walk you through it step-by-step.”
A. We prefer to keep such commonplace or even clichéd phrases, some of which are listed in hyphenated form in standard dictionaries, open when they appear after the noun they modify or when they are used adverbially:
step-by-step recovery (where “step-by-step” is a phrasal adjective preceding the noun it modifies)
but
feelings that were out of date (because “out of date” follows the noun it modifies)
and
walking across the continent step by step (because “step by step” is functioning as a phrasal adverb)
See CMOS 5.92, 5.93, and 5.161 for more information. For examples, see the hyphenation table at 7.89.