Cash payment limits: non-compliant large cash payments to a payee preclude deduction unless made by prescribed non-cash methods. Section 40A(3) denies deduction for expenditures where aggregate daily payments to the same person exceed the statutory cash threshold unless payments are made by account payee cheque, bank draft, electronic clearing through a bank account, or other prescribed electronic modes; it targets aggregate daily cash payments to the same payee to ensure use of traceable non-cash instruments.