such other severe financial hardship situations as may be determined by the housing authority. If a resident requests a hardship exemption and the authority reasonably determines the hardship to be of a temporary nature, an exemption shall not be granted during the 90 day period beginning upon the day in which the request for exemption is made to the authority. A resident may not be evicted during such 90 day period for nonpayment of rent. In such a case, if the resident thereafter demonstrates that the financial hardship is of a long-term nature, the authority shall retroactively exempt the resident from the applicability of the minimum rent requirements for such 90 day period. Notwithstanding the provisions of section 49 of chapter 271, the authority may impose a late penalty of $25 for failure to pay rent due. For the purpose of determining continued eligibility, pursuant to regulations of the department, the authority shall determine the appropriate unit size based on the composition of each tenant household. If a tenant is determined to be overhoused, such tenant shall be subject to transfer to a unit of appropriate size, as required by the lease. If an overhoused tenant household refuses a transfer to an available unit of appropriate size, the tenant shall be subject to a minimum rental fee of 150 percent of the tenant's rent. Any deficiency in the budget of a housing authority caused by such reduced rental shall be paid by the commonwealth to the housing authority in an amount equal to the difference between the tenant's rent and the prorated cost of operating that unit. The commonwealth, acting through the department, may make payments in advance on account of such deficiency in such amounts and at such times as it deems proper. The prorated cost of operations