AO Code requirement: applicants must obtain and provide jurisdictional AO Code when applying for PAN or TAN. Provision of the AO Code is mandatory when applying for PAN or TAN; the AO Code (Area Code, AO Type, Range Code and AO Number) identifies the jurisdictional Assessing Officer and must be obtained and entered by the applicant using the specified online AO search tools for PAN and TAN to retrieve the correct AO Code prior to application submission.