(a) A tenant in a moderate rental housing project shall vacate the dwelling unit occupied by such tenant not later than sixty days after the housing authority or developer has mailed to such tenant, properly addressed, postage prepaid, written notice that the annual income of such tenant’s family, determined under § 8-72, is in excess of that permitted for continued occupancy of such dwelling unit under said section. Upon the failure of such tenant to vacate such dwelling unit on or before the expiration of such sixty-day period and as long as such tenant continues to occupy such dwelling unit after the expiration thereof, such tenant shall be obligated, notwithstanding the provisions of § 8-72, to pay to the authority or developer monthly as rent for such dwelling unit an amount equal to the going rental therefor as fixed by the authority or developer plus an amount equal to two per cent of the excess of the annual income of such family over that permitted for continued occupancy of such dwelling unit under § 8-72.

(b) Notwithstanding the provisions of subsection (a) of this section, if the eviction of such tenants would result in or increase the number of vacancies in such project, the housing authority or developer may request approval of the Commissioner of Housing to permit continued occupancy by tenants having an annual income over the maximum limits established for such project and rental of existing vacant units to tenants having an annual income over such maximum limits. If the commissioner finds that the vacancy rate which would result from refusal to grant such approval may result in an inability of the project to provide an income adequate for debt service, if any, administration, including the state service charge, other operating costs and reserves for repairs, maintenance, replacements and collection costs, the commissioner may approve such occupancy for a period of one year, subject to renewal for additional one-year periods. The amount fixed as rent for units so occupied pursuant to this subsection shall be determined as provided in subsection (a) of this section but in no event shall such rent be in excess of one hundred thirty-three per cent of the going rental as established pursuant to § 8-72.