SECTION 1.  Section 6 of chapter 62 of the General Laws is hereby amended by inserting after paragraph (a) the following new paragraph:—

(b) A credit of $600 shall be allowed against the taxes due if the taxpayer has provided more than one-half of the support for an elderly relative who has attained the age of 70 before the taxable year, or for a totally disabled relative with Alzheimer’s Disease, provided that the relative resided with the taxpayer for more than 6 months of the taxable year and provided further that the adjusted gross income of the relative does not exceed $20,000 in the case of a single return and $35,000 in the case of a joint return. If the credit provided in this section reduces the tax to zero, the taxpayer shall be entitled to a refund equal to the amount by which the amount of the credit exceeded the amount of tax due.