Pupils had accused the Welsh Government of “abandoning them” after 42% of grades were lowered by the exams watchdog.
Education Minister Kirsty Williams has confirmed appeals will be allowed if “there is evidence” pupils should have received higher grades.
She said it gave “clarity” to students.
Ms Williams said the broadening of appeals by Qualifications Wales, meant students could now appeal if there was “evidence of internal assessments that has been judged by the school or college to be at a higher grade than the grade they have been awarded”.