Hello there,

To apply for gap certificate you have to go to the district court or you can contact to any lawyer or advocate. It is a legal affidavit which will be issued by court which will consider as proof for the reason for which you have taken a gap in your education.

Since you have given 12th in 2018 and then improvement in 2019 and applied in a college in 2020 then you will have a gap of one year. So your affidavit will be for one year gap.

Good luck!!