(2) If any defect is noticed in the application in Form No. 3CED or if any relevant document is not attached thereto or the application is not in accordance with understanding reached in any pre-filing consultation referred to in rule 10H, the Director General of Income-tax (International Taxation) (for unilateral agreement) and competent authority in India (for bilateral or multilateral agreement) shall serve a deficiency letter on the applicant before the expiry of one month from the date of receipt of the application.
(3) The applicant shall remove the deficiency or modify the application within a period of fifteen days from the date of service of the deficiency letter or within such further period which, on an application made in this behalf, may be extended, so however, that the total period of removal of deficiency or modification does not exceed thirty days.
(4) The Director General of Income-tax (International Taxation) or the competent authority in India, as the case may be, on being satisfied, may pass an order providing that application shall not be allowed to be proceeded with if the application is defective and defect is not removed by applicant in accordance with sub-rule (3).
(5) No order under sub-rule (4) shall be passed without providing an opportunity of being heard to the applicant and if an application is not allowed to be proceeded with, the fee paid by the applicant shall be refunded.
Reference/Source: Check at Income Tax site for latest version of the Rules - link