Rectification of errors apparent on the face of record

161. Without prejudice to the provisions of section 160, and notwithstanding anything contained in any other provisions of this Act, any authority, who has passed or issued any decision or order or notice or certificate or any other document, may rectify any error which is apparent on the face of record in such decision or order or notice or certificate or any other document, either on its own motion or where such error is brought to its notice by any officer appointed under this Act or an officer appointed under the Central Goods and Services Tax Act or by the affected person within a period of three months from the date of issue of such decision or order or notice or certificate or any other document, as the case may be: Provided that no such rectification shall be done after a period of six months from the date of issue of such decision or order or notice or certificate or any other document: Provided further that the said period of six months shall not apply in such cases where the rectification is purely in the nature of correction of a clerical or arithmetical error, arising from any accidental slip or omission: