Dear student,

As your family income is less than Rs. 8 lakhs per annum then you are eligible to get an obc ncl certificate. Your capital gain income is not considered during the making of obc ncl certificate. For income proof only income certificate is required. And if income is really under Rs. 8 lakhs per annum then you are definitely eligible for getting an obc ncl certificate.

And this certificate is only valid for one year. And after that you have to reissue a new onw or have to do a renewal of your category certificate.