"The point the IRS emphasizes ... is that the employee must actually return from the unpaid leave of absence before they may be treated as a new employee. If you use the monthly measurement method to determine full-time status, this distinction has little effect; unpaid, non-FMLA leave does not count as hours of service towards the 130 hour per month requirement, so you may not have to offer coverage for some or all of the months the employee is absent. However, if you use the lookback method to determine full-time status, an employee who was determined to be full-time and offered coverage during a stability period must continue to be offered coverage through the end of the stability period while on an unpaid leave, even after 13 continuous weeks."