Company A matches 75% of first 8 percent of 401(k) deferrals. Employer may make additional discretionary matching contribs. Company B matches 50% of first 8% of 401(k) deferrals, and may also make additional discretionary matching contribs. Company B acquires Company A and merges Plan A into Plan B. Can plan retain Company B matching formula? And does this result in Company A participants becoming 100% vested in their matched contributions as of the merger date? Any other issues?

You don't have to vest Company A amounts since you are not terminating the plan. Company A match will continue to vest. Just curious, do A and B both have the same vesting schedule?

Since these are not safe harbor matching amounts you can change them at any time.

Thank you for reply. Company A 5-year cliff and Company B 6-year graded (20%)