If you are a builder constructing flats for sale, you are generally eligible to claim ITC on your construction inputs. However, whether you can claim ITC on specific "lightings and fittings" depends on whether they are classified as part of the immovable property (blocked) or as separate, movable assets (eligible). Given the litigious nature of this specific classification, it is highly recommended to consult with a tax professional to assess the nature of the fixtures in your project to ensure compliance and avoid potential interest and penalties under Section 17(5).