A registrant who cancels a registration during a calendar year may qualify for a partial abatement. To be eligible, however, such a registrant must also either (a) transfer title to the vehicle or (b) move out of Massachusetts and register the vehicle in some other jurisdiction. For a registrant who so qualifies, the assessors, not the Registry, must calculate the amount of the abatement for which the registrant is eligible. A registrant will never qualify for an abatement on any vehicle for any month during which the vehicle was registered for any portion of that month.