SECTION 1. Section 6 of Chapter 62 in the General Laws is hereby amended by adding the following:

(1)   In paragraph (2) of subsection (k), inserting, after the word “allowed” in line 350, the following: - (a)

(2)   In paragraph (2) of subsection (k), adding the following: - or (b) a percentage credit equal to at least the number of years in excess of twenty that the owner or tenant has paid property taxes on the residential property, but not to exceed thirty percent.

(3)   In subparagraph (i) or paragraph (3) of subsection (k), inserting, before the word “the” in line 354, the following: - in instance (2)(a) above

(4)   In subparagraph (ii) of paragraph (3) of subsection (k), inserting, before the word “the” in line 357, the following: - in instance (2)(a) above

(5)   In subparagraph (ii) of paragraph (3) of subsection (k), adding the following: - or in instance (2)(b) above the assessed valuation of the residence does not exceed the median valuation of residential properties in that municipality by more than twenty percent. In instances in which the valuation of the residential property exceeds by a certain percentage the median in the municipality, the credit shall be reduced by the equivalent percentage.