Chime in is an intransitive phrasal verb -- it never takes a direct object, and the particle "in" never drops. Once you have that fixed, the only real decision left is which preposition follows it, because "chime in" behaves differently depending on whether you're introducing your content, your topic, or your purpose.
Introducing content: chime in with
When you're naming what you're actually contributing -- a comment, a question, an idea -- "with" is the preposition that connects "chime in" to it.
"During the town hall, employees were encouraged to chime in with any questions regarding the merger."
This is also where the most common learner error shows up: dropping "with" and treating "chime in" as if it could take the content directly, the way "raise" takes "a question." It can't -- the particle "in" already does the work of "joining," and "with" is what introduces what you're joining in with.
Naming the topic or purpose: chime in on / chime in to
When you're pointing at the subject under discussion rather than your own content, "on" is the natural choice. When you're naming the reason you're speaking up, "to" plus a verb does that job.
"I'd like to chime in on the point Sarah just made."
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Start learning for free →"Chime in on the debate" and "chime in to support" both work for the same reason: "on" marks the topic you're addressing, "to" marks the purpose behind speaking.
A related fixed phrase worth knowing is the invitation form, "feel free to chime in" -- the standard way a meeting host opens the floor for exactly this kind of brief, unscripted contribution.
What doesn't collocate
The clearest mistake is giving "chime in" a direct object, as in "the consultant chimed in his expertise during the workshop" -- expertise has to be introduced with "with," so the correct form is "chimed in with his expertise." A second mistake is dropping the particle entirely: "we are waiting for the CFO to chime to the discussion" is missing "in," and no preposition can substitute for it. A third is reaching for the wrong preposition to describe the setting, as in "chime in through the meeting" -- "during" describes timing, but it isn't the preposition "chime in" itself takes.
Practice scenarios
Practice using chime in in situations like:
- inviting quieter colleagues into a discussion with "feel free to chime in"
- adding a brief supporting point to something a colleague just said
- responding to a direct question from leadership by chiming in with your view
Useful practice phrases:
- "Feel free to chime in with any questions."
- "I'd like to chime in on the point [colleague] just made."
- "[Name] chimed in with a quick suggestion before the meeting moved on."