Section 21E(4)(ii) in Kerala General Sales Tax Rules, 1963
(ii)Where the irregularity detected is the failure to prove the claim of any exemption or reduction in rate of tax, the best judgement assessment shall be limited to the disallowance of the claim of such exemption or reduction, as the case may be. Where any such claim of exemption or reduction in rate of tax is disallowed, in addition to the tax that becomes additionally payable, interest under sub-section (3) of section 23 and twice the interest as penalty shall be demanded or levied.