Exclude customer in a customer search results if a custom entity date field value in the customer record is equivalent to 3 years ago minus 1 day

 

On the Saved Customer Search page, go to Criteria tab > Standard sub tab and set the following formula filter:
Filter	Description	Formula
Formula (Numeric)	is 0	Case when trim({custentity_xx})=trim(add_months({today},-36)-1) then 1 else 0 end
Notes :
Replace {custentity_xx} with the internal iD of the specific custom field.
The number 36 represents 3 years ago (12 mos. * 3)