lam not submit ews certificate at the time main registration time can i submit jee advanced time

Hi

The final say lies with the concerned authority I would suggest to get in touch with them through their helpline according to your zone.

https://jeeadv.ac.in/contact.php

You can also check the FAQS section of JEE advanced 2021

https://jeeadv.ac.in/faqs.php

FAQs regarding category change

QUESTION 7: During JEE (Main) 2020 registration I have declared my category wrongly. Can I correct it during JEE (Advanced) 2020 registration?

ANSWER: No. Category declared during JEE (Main) 2020 registration cannot be changed during JEE (Advanced) 2020 registration.

QUESTION 8: I have declared my category as GEN-EWS during JEE (Main) 2020 registration. But I do not belong to GEN-EWS. Can I register for JEE (Advanced) 2020?

ANSWER: Yes, you can register by declaring that you do not belong to GEN-EWS provided your JEE (Main) 2020 score is above the General Cut-off. If your JEE (Main) 2020 score is below the General Cut-off you are not eligible for JEE (Advanced) 2020.

Everyone has their own version of the story regarding this .since you want to change from general category to GEN - EWS they would allow it but its better to consult them first instead of acting on your own accord so as to prevent any further headaches.

All the best!