<h1>Affordable housing project notification through Form 18 is mandatory for claiming tax benefits under the specified business regime.</h1> Form 18 is the prescribed application for notification of an affordable housing project as a specified business under section 46 of the Income-tax Act, 2025, and filing it is mandatory for availing the tax benefits available under that provision. The form requires the assessee to furnish particulars of the assessee, the specified business, the proposed project, compliance with prescribed conditions, and other project-related details, including project location, unit-wise area particulars, investment, title to land, development agreements, and a declaration certifying correctness of the information furnished.