This Rule establishes the conditions under which an Incorporated Body may file an amended tax declaration. It is permissible only if a material, accounting, or legal error is found and no tax assessment for that year has been issued. The filing date of the amended declaration determines the application of the Income Tax Decree and any delay penalties. The procedure involves a formal request to the Tax Department, which has 30 days to approve or reject it; silence implies rejection. Special cases require separate consultation.