This bill authorizes municipalities to enact and enforce rent stabilizing ordinances. The bill defines "allowable rent increase" as the standard amount that the rent of a covered unit may be raised within the following calendar year. The bill also defines other terms such as "board or body" and "fair return on investment." The bill allows municipalities to enact ordinances that create a generally applicable allowable rent increase percentage above which an owner of covered property may not raise a tenant's rent over a 12 month period. The ordinance or regulation shall not limit the amount of the allowable rent increase percentage to less than 5 per cent plus the percentage increase in the Consumer Price Index for the New England Region over the preceding 12 months. The bill also allows owners of covered properties to demonstrate that due to increases in property taxes, owner paid utilities, maintenance and repairs, and other reasonable and necessary operating costs, a rent increase beyond the maximum allowable increase set forth in the ordinance shall be allowed to the extent that such increase is necessary to enable the owner to realize a fair return on his or her investment. The bill also establishes a process for owners to appeal an order denying their application for exemption. The bill expires 5 years from the effective date of the ordinance.