Hello aspirant,

Yes improvement exams are absolutely valid for Jee exams. If you haven't got 75% in yours boards then you can absolutely give for improvement exams. But if 75% criteria has been removed by NTA for 2021 exams. If you study harder and try to crack jee this year, there is no need of improvement exams.

For Jee 2022 eligibility criteria you may go through the link https://jeemain.nta.nic.in/eligibility-criteria/

Hope this helps you:)