Sir...I have filled UPSC 2021 FORM... as an open candidate bcz I hadn't EWS certificate... now prelims has postponed..Can I apply in mains for EWS... I will have EWS certificate soon ...
No! Once the correction window gets closed you can't update information to your registered account. Now as you will fill the Mains form you will have the prestored data of your account so you will not be able to change them.
Sorry but this is the reality!
For UPSC CSE preparation tips you may visit the link provided below:
https://competition.careers360.com/articles/how-prepare-for-upsc-ias
I hope this answer helps. All the very best for your future endeavors!