Eligibility Criteria with automatic performance rating

Content

Hi Expert, 

We have requirement where  client want system to understand Leave of Absence eligibility criteria for performance review as following: In the event a worker is on leave of absence during a Performance Period and has less than 90 days of active employment Performance Period, the worker will not be eligible for a performance review and no performance document should be created for him or her for the current year. However, for such a worker rating will get automatically coded as "Not eligble " in the system.

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I understand we can create Fast formula to exclude employee those who have less than 90 days active. But how we will give rating " Not Eligible"  to those employee ?