Can rectification u/s 154 file after the the expiry of 4 years. In my case there was an outstanding demand of Rs.31000(sec code 143 1 a) for AY 2008-09. It is comes to notice only after receiving the refund adjustment letter for AY 2016-17. As per the return filed for the AY 2008-09 there was a refund of Rs.2000. Please advise me in this regard