Merging Safe Harbor Plan Mid Year

Company A sponsors a Safe Harbor ( 3%) auto enrollment plan.  They recently purchased another company via a stock purchase. Purchased company is also a Safe Harbor (3%) auto enrollment plan. They intend to merger (not terminate) the acquired company's plan  into Company A's plan.

Trying to figure out if merger can occur mid year, or if  it has to wait until 1/1/2020.

Thanks you.

52626, I think that if (and I'm not completely clear on your facts) the safe harbor provisions are identical (i.e., 3% nonelective), the merger could be analyzed as in effect a plan amendment that is not a prohibited amendment under Notice 2016-16. But that is really "hypothetically" speaking, since I obviously have not reviewed your facts/documents.