Nidhi, you haven't mentioned the Board you studied your 12th in. Every Board has its own improvement/supplementary examinations criteria. In general, the students who have failed in 2 subjects can appear for Supplementary exams in the next immediate available session that the board opens. For example, those Candidates who have appeared for their 12th in 2020 through GSEB board and have failed, can appear for supplementary exams when the process opens tentatively in the month of August. We would suggest you to clarify the same by contacting the helpdesk: administrator@gseb.org (mailto:administrator@gseb.org) if it is for GSEB board. Technically you should be able to appear for July 2020 session.