Missed Deferral - automatic enrollment

Plan has immediate entry for deferrals.    A participant was hired on 9/17/2013.   (2/28 PYE).   Switched to 12/31 pye at 12/31/2014.   2% initial deferral, no increase.   

They have never included this employee, so have to make up for 2/28/2014, 12/31/2014, 12/31/2015, 12/31/2016, 12/31/2017 and January and February 2018. 

Is the missed Deferral, 2% or  do I use the ADP and give them 50% based on that?    

Never had this with automatic enrollment.   

Thanks

Was the auto-enrollment notice provided to the participant? I.e. were they given an opportunity to enroll?

No.    There is a new person at the company and she sent me the 12/31/2017 census and included this participant.  This is the 3rd contact for the plan in 5 years.      When I asked why she was never on the census prior, she had no Idea and couldn't find a reason why.    She is part time, but had over 1,000 hours in each plan year.   She also did not receive a profit sharing contribution in each of the years.    

Given that no notice was provided to the employee, I lean toward using the higher of the two (50% of ADP vs. 50% of missed ACR). Plus earnings.

I was just informed that this person's last day was on Tuesday.     They still have to give this participant the missed contributions?  correct? 

I do not believe their terminating employment should preclude them from receiving the corrective contributions for prior years.