Section 35AC deduction covers eligible welfare projects, subject to approval, prescribed certification, and no double deduction. Deduction under Section 35AC is available for expenditure on eligible projects or schemes promoting social and economic welfare or upliftment of the public, subject to the limitation that no deduction is available for assessment years commencing on or after 1 April 2018. The deduction applies to payments to a public sector company, local authority, or approved association or institution, and a company may also claim for direct expenditure on an eligible project. The claim must be supported by the prescribed audit certificate, and the same expenditure cannot be claimed again under any other provision of the Act.