<h1>Authorised Income-tax Practitioner registration through Form 171 requires eligibility details, supporting documents, and one-time filing.</h1> Form 171 is the prescribed application for registration as an Authorised Income-tax Practitioner under section 515 of the Income-tax Act 2025 and must be filed with the jurisdictional Chief Commissioner or Commissioner of Income-tax. The application is mandatory for recognition in that capacity, may be filed after eligibility arises, and is a one-time filing unless otherwise directed. It requires applicant particulars, eligibility details, qualifications, supporting documents, and relevant firm or association details. On approval, the applicant's name is entered in the Register of Income-tax Practitioners and a Certificate of Registration is issued.