I have an income certificate issued on 21st June 2018.is this certificate applicable for the registration of counselling 2021 . in the certificate they write as it is valid for 4 years
You didn't mentioned the name of the examination for which you are sitting in counselling. In general, every examination provides the date of the issuing certificate for the counselling. If you have a certificate that meets the requirement as per the official authority is termed to be valid. So I would recommend you to check the official brochure of the examination you are concerned about and find what the specifics asked and accordingly you will get the idea that is it valid or not.
I hope this answer helps. All the very best for your future endeavors!