Switching carriers at renewal can lower premiums or improve networks, but it can reset deductibles and out-of-pocket accumulators and change which providers are in network. Timing, participation, and contribution rules all factor into the decision.
Usually not for a fully-insured plan, which runs a 12-month contract and changes at renewal. Mid-year changes are generally limited to qualifying events, though switching carriers mid-year is possible in some cases (and restarts the plan year).
Usually not. Switching mid-year restarts the plan year, resets deductibles and out-of-pocket totals, and can disrupt provider relationships, so it’s generally best to change at renewal unless there’s a strong reason.