INCOME TAX APPLICABILITY TO STs IN MEGHALAYA

Dear Expert,

One of my Clint residing in Ri-Bhoi district of Meghalaya claim that they are not liable to pay income tax as they are schedule Tribes residing in Meghalaya. But as per my view only those STs residing in Jaintia, Garo and Khasi hills of Meghalaya (as per sixth schedule) are exempt from income tax under Section 10(26). Plz clarify.