How to account for length of service in absence donation approvals?

Summary:

Is it possible to account for the length of service in the absence donation approval flow?

Content (required):

We have a policy for donation of sick leave that requires the employee to be with us for at least a year. I have tried using getRequestorInformationByUserNameResponse.personStartDate, but this does not account for rehires and may include time where this person was a contact and not an employee. I have also tried getRequestorInformationByUserNameResponse.effectiveStartDate but did not return the hire date. Is there another option to return the employee's hire date or another date/field that could be used to get the length of service?