Section 18. Land qualifying for valuation, assessment and taxation under this chapter shall be subject to special assessments or betterment assessments to such pro rata extent as the service or facility financed by such assessment is used for improving the agricultural or horticultural use capability of said land or for the personal benefit of the owner thereof. Any such assessment shall, however, upon application, be suspended during the time the land is in agricultural or horticultural use and shall become due and payable as of the date when the use of such land is changed. In the event only a portion of a tract of land which benefits from a suspension of payment is changed from such use, the assessment shall become due and payable as of the date when the use was changed only to the extent of and in the proportion that the frontage of such portion bears to the street frontage of the entire tract of land which originally benefited from a suspension of payment. Upon full payment of a portion of a suspended assessment, the tax collector may dissolve the lien for the assessment insofar as it affects the portion of the land changed from agricultural or horticultural use. The lien for the portion of the original assessment which remains unpaid shall continue and remain in full force and effect until dissolved in accordance with law. A request for such release shall be made in writing to the tax collector, and shall be accompanied by a plan and such other information as is required in the case of a request for a division of an assessment pursuant to section fifteen.

Payment of the assessment and interest on it shall be made in accordance with section 13 of chapter 80, but any interest shall be computed from the date of the change in use.