Yes there are two types of EWS certificate for central and state. In Assam, the annual income for State EWS is Rs. 6 lac/annum (maximum) and for the central EWS you have the annual income limit to be Rs. 8 lac/annum(maximum).

**You can download the rules and regulations of EWS for Government of Assam by typing 'EWS form Government of Assam' on google search. Similiarly you can approach for the central EWS.

I hope this might help. All the very best for your future endeavors!