short plan year

If a client wishes to start a new plan that has deferrals and safe harbor match only (does not have an Employer Match or Profit Sharing provision), must the plan have a short plan year  for the first year to accommodate the notice requirement? Or can the plan year begin on 01/01/21 with a special effective date of 04/01/2021 for deferrals and safe harbor, even when the there's no match or profit sharing? I'm trying to avoid having a short plan year for the limitation year and include comp for the entire 12 months of the year. 

Why a 4/1 start date? Best practice is to give the employees 30 day notice, even if it isn't technically required for a new start up plan. 

I'm guessing you want the Safe Harbor Match formula to be calculated on an annual basis and not per payroll basis if you are wanting the full income counted. 

But I would make the safe harbor match start date as 1/1/2021 even if the deferral start date is 4/1/2021. 

My understanding of the regulations is that you cannot start safe harbor provisions prior to deferral provisions. Is that not accurate?

I believe you could make the effective date retroactive to 1/1/2021 with discretionary profit sharing and the deferral and safe harbor portion prospective, such as your 4/1/2021 start date for those portions of the plan.