The RMV is scheduling appointments to register vehicles three days in advance.  These appointments are booking quickly and are given for “essential” transactions only.

Here is the RMV link for Covid-19 updates

The only transactions that will be processed at service centers are those that the RMV considers ‘essential’. Examples of ‘essential’ transactions include obtaining a commercial driver’s license or commercial learner’s permit to assist with the supply chain during the State of Emergency declaration, registering a newly purchased vehicle as your primary mode of transportation for employment or obtaining medication and other necessary treatments, or transferring your license or registration from another state for residency requirements. Examples of ‘non-essential’ transactions include registering a motorcycle as a secondary mode of transportation, obtaining a REAL ID unless part of a new Mass ID issuance or out of state transfer of a driver’s license/ID, or registering a boat or utility trailer or camper for recreation purposes. Customers who need to complete ‘essential’ transactions are required to make an online reservation, and customers arriving without an appointment will be asked to leave and make one online to return at a future date

If a customer makes an appointment at the RMV and shows up to process a “non-essential” transaction such as registering a secondary vehicle they will likely be turned away.  Please be mindful of this and plan accordingly.