If the IRS rejected the return for a missing 8962 then you MUST enter the 1095-A before the return will be accepted. If you mail the return without this form it will delay the processing for MONTHS until you provide the missing form ... so do it right now and avoid the future pain.
They believe you have a 1095-A with your name on it for 2021 so check with the Healthcare Marketplace for the 1095-A form ... they have been available online since 1/6 but have not yet been mailed out. www.healthcare.gov
Maybe you had the ACA insurance for a month in early 2021 or you were on your parent's policy ... you need to get to the bottom of it.
