Dear Megha,

EWS ( economic weaker section) is the general category in which annual family income is less than rupees 8 lakhs and family do not belong to any reserved category like STs, SCs, OBCs etc.  It is not purely income based but it depends upon the central govt. ,sometimes it is categorised on the basis of property. Earlier it was not for every state but now it is for every state in India.

And yes your EWS certificate is valid in central government job.

I hope you got your answer.

Good luck.

Thank you!