Section 11B. Claim for refund of duty.-
(1) Any person claiming refund of any 2[duty of excise and interest, if any, paid on such duty] may make an application for refund of such 3[duty and interest, if any, paid on such duty] to the Assistant Commissioner of Central Excise or Deputy Commissioner of Central Excise before the expiry of one year from the relevant date in such form and manner as may be prescribed and the application shall be accompanied by such documentary or other evidence (including the documents referred to in section 12A) as the applicant may furnish to establish that the amount of 2[duty of excise and interest, if any, paid on such duty] in relation to which such refund is claimed was collected from, or paid by, him and the incidence of such 3[duty and interest, if any, paid on such duty] had not been passed on by him to any other person:
Provided that where an application for refund has been made before the commencement of the Central Excises and Customs Laws (Amendment) Act, 1991, such application shall be deemed to have been made under this sub-section as amended by the said Act and the same shall be dealt with in accordance with the provisions of sub-section (2) substituted by that Act;
Provided further that the limitation of one year shall not apply where any 3[duty and interest, if any, paid on such duty] has been paid under protest.Thanks
Refer the bold text in bold.