ADP Test - missed deferrals

[blue]

Plan administrator thought participants were to start deferring first of month after satisfying eligibility conditions. Document states enter the plan the day eligibility conditions were met.

I can find where EPCRS states if the participant was not given the opportunity to defer for the entire plan year you take them out of the ADP test. However, I cannot find any guidance for participants who are briefly excluded where the error is not discovered until after the end of the plan year.

I am assuming you do not take the person out of the test. This assumpiton gives rise to my next question -

Do you use full year compensation, compensation from date they started deferring or something else for the ADP test?

If you use compensation from the time they actually deferred, it might make the participant neutral when you use the average of the group to calculate the required QNEC for the missed opportunity cost. Seems logically but is it the right approach.

Any suggestions would be greatly appreciated.