Dear student,

Kindly check the guidelines of the university/college wherein you are applying for counselling since they mention the year for which any of the certificate is required, however, if it is not stated or specified you may simply upload the income certificate which you have as of now and if in case it isn't acceptable to the concerned authority submit the latest one.

However, it would be better to have a latest income certificate because income as a matter of fact might change since the duration from 2016 to 2021 includes a span of 5 years. also, for better clarification , mail the concerned authority or the helpline number of the college/university and do check the guidelines as well.

as of now you may upload the old 2016 certificate and apply for a new one as well for a safer side.