MRDP was informed by USSF last year (2016) at the annual workshop that all re-registrations must be completed by June 30 of each year. If a referee fails to re-register by that date, they can not be registered for the balance of that registration (calendar) year. In years past referees that had let their registration lapse we allowed to attend an entry clinic and then be active, but USSF's policy not longer allows that.
In addition, the USSF recommends that any registration that has lapsed for 3 years or more requires that person to retake the entry course in it's entirety. The previous re-registration applies as well, so that referee won't be re-registered until January 1 of the following year, and they are considered a re-registration, not a new referee. MRDP migrated to game officials in 2016, and the software is hard coded to enforce these national policies.
