Suraj, Yes, you can surely use the EWS Cerificate issued by the Central government for the state level exams as the EWS category is specified by the central government and if you are eligible to that quota ie if you fulfill its' eligibility criteria, then you can get the EWS Certificate from your city officials. However, you have to take one point into consideration that some states like Maharashtra, Madhya Pradesh etc. have different criteria for eligibility to the EWS quota and if you want to apply in these states, then you would have to see those eligibility criteria as well, however, in most cases, the Central EWS certificate will suffice and you would be able to use it for your purpose.