Need Absence Duration in Validation Formula

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Hi,

     I am trying to use following logic in my sick accrual plan validation formula.

I want to capture Absence logged by person till date from the start of the year to validate.

absence since 1jan till date >40 then send a error message that you have reached annual maximum limit to utilize absences. 

Now I want to how can we get this absence logged till date value in fast formula.

Regards