Mid-year change from SH Match to 3% NE?

Client has a SH match in their 401(k) plan.

1 - Could they change to a 4% SHNE for 2021? 

2 - Could they change to a 3% SHNE for 2022?

Thanks! 

1. No. Too late to change 2021.

2. Possibly. If the employer is operating at an economic loss, or if the safe harbor notice provided that the safe harbor may be suspended mid-year, then they could suspend the safe harbor match and adopt the retroactive safe harbor which may be 3% or 4% depending on timing. 

See Notice 2016-16 III.D.3 and Notice 2020-86 Q&A-8 for more info.