A controlled group decides to spin off one of the companies in the controlled group. The spun-off company will adopt its own DC plan, and all of the DC accounts in the controlled group will be transferred to the new plan.

Must the new plan credit vesting and eligibility service with the controlled group prior to the spin-off?

Don't know, but it seems to me the plan spinoff would occur prior to the corporate spinoff. If that is the case, then the answer should be yes. I think the answer for vesting service is yes in any case. Perhaps someone with some actual intelligence can help.