Income tax return filling and got a notice u/s 143(1)

dear sir a an individual file income tax return foe a.y 2018-2019 in june 2018 and claim refund of amount 19500 further he realised that income shown by me is less than actual so that he revised the return from increased value.A refund has been credited in my account according to original return file but he check the account after revisin the return. on jan five he got a notice u/s 143(1) demanding 14000 tax amount.pls suggest me what can he do?either rectify the return or revised the return or any more?