Section 16(2)(a) in Tamil Nadu Village Panchayats (Assessment and Collection of Taxes) Rules, 1999
(a)The annual rental value of house shall be deemed to be the gross annual rent at which the house may reasonably be expected to let from month to month, or from year to year, less a deduction of ten per cent of such annual rent and the said deduction shall be in lieu of all allowances for repairs or on any other account whatsoever.