The department confirmed that 12,292 students in respect of 33,677 grades had lodged an appeal.
The deadline was 5pm on Wednesday. Despite controversy over results that were downgraded, appeals will not consider the difference in marks given by a school and the grade delivered by the Department of Education.
The appeals process will only consider errors in the transmission and processing of student data.
Students who are unhappy with their results will still have the option of sitting the Leaving Cert exams on November 16th.
Details on how the exams will be conducted have not yet been confirmed.
The first of what may be several High Court challenges against the system used to calculate Leaving Certificate results during the Covid-19 pandemic began yesterday.
