An improvement to any real property used for residential purposes
as a one-, two-, or three-family residence shall be exempt from taxation
to the extent of any increase in value attributable to such improvement
if such improvement is used for the purpose of facilitating and accommodating
the use and accessibility of such real property by (a) a resident
owner of the real property who is physically disabled, or (b) a member
of the resident owner's household who is physically disabled, if such
member resides in the real property. This exemption shall also apply
to improvements constructed prior to the effective date of this article.
Eligibility for such exemption shall be pursuant to the procedures
and standards set forth in § 459 of the Real Property Tax
Law and administration thereof.