The validity of EWS certificate in Jammu and Kashmir is 1 Financial year. For example, if you have got a EWS Certificate done in 2020, it's validity would expire by April 2021 because that is when the Financial year ends. You have to get it renewed again.  EWS reservation is applied across all Educational Institutions- Private, Government and Semi-Government. An EWS Certificate issued by a local authority with duly signed and attested is good and considered authentic enough. Even if it is at Tehsildar or SDO level, it is still considered good.
You will need 3 documents:

1. DOCUMENTS FOR DATE OF BIRTH: You have to provide any of the mentioned documents as said above in the article body.

*Birth certificate under the Birth. Death and Marriage Certificate Act. 1969.

*Hospital/Auxiliary urse and Midwife.(ANM) register record.

*Anganwadi Record.

*Declaration of age of the child by the parents or guardian.

2. DOCUMENTS FOR PROOF OF PRESENT RESIDENTIAL ADDRESS:-

*Ration card in the name of Parents having name of the Child in Ration card.

*Domicile certificate of child or his/her parents.. .

*Voter Id card of any of the parents.

*Electricity Bill/MTNL telephone bill/Water bill.

*Unique Identity Card (Aadhar) of Mother/Father/Child issued by Govt. of India.

*Passport in the name of any of the parents or child

3. DOCUMENTS FOR PROOF OF ECONOMICALLY WEAKER SECTION (EWS):-

*Income. certificate issued by ae Revenue Officer not below the rank of Tehsildar

*BPL Ration Card (Yellow coloured)

*AAY Ration Card (pink coloured)

*Food Security card.issued by Food & supply Dept.(GNCT of Delhi)
With these documents you can prove that you belong to EWS category

Hey aspirant,

The validity period for Economically Weaker Section Category certificate is generally 1 year for almost all states.

If you have any doubt then you can check further details in the Department of revenue website of your state. And you can confirm if ut is 1 year or 6 months.

Hope this helps,

All the best!