The rehire utility looks for breaks in service between payroll periods. It will apply either the 13-week consecutive absence rule – any employee who was absent for at least 13 consecutive weeks – or the ACA-defined rule of parity. 

The rule of parity states that if an employee had previously worked for you at least 4 weeks, and their subsequent break in service was greater than what they previously worked for you, you can classify them as a rehire upon their return to service.