Section 5. In any city or town in which a program of revaluation of all property therein has been or shall be undertaken and completed in time to be reflected in the assessments for the next succeeding tax year but not in sufficient time to permit landowners to make application prior to October first of the year preceding the tax year for the valuation, assessment and taxation of their lands for the ensuing tax year on the basis of being maintained in recreational use, any such application filed with the board of assessors after October first and not more than thirty days following the mailing of the tax bill containing the new valuation shall be deemed to have been timely made for the tax year of the revaluation program, notwithstanding any provision of this chapter to the contrary. If such application is approved and the lands qualify for valuation, assessment and taxation as lands maintained for recreational use in the ensuing tax year, the portion of any tax assessed for such year which is in excess of the tax which would have been assessed on such lands had such application been timely made and approved shall be abated.