Completion of assessment 21

Mr. X was issued notice under section 142(1) to file return of A.Y. 12-13 on 7.7.2021 , Mr. X submits return on 8.8.2021 and A.O. issued notice u/s 143(2) on 10.10.2021. Till when A.O. needs to complete assessment u/s 143(3) ?