Students in Wales can now appeal their A-level grades if they were lower than the predicted grades awarded by teaches following a backlash over results.
WJEC will release further details on the appeals process from early next week.
Grades will be protected so that student will not be at risk of a lower mark following the appeal.
Education Minister Kirsty William has said all appeals will be free.
She said: “Earlier this week I directed Qualifications Wales to broaden the grounds for appeal for A levels, AS, Skills Challenge Certificate and GCSEs.
"Today, they have now confirmed what this means for students. I accept that learners wanted and needed more clarity, and I believe this achieves that.
“Qualification Wales and the WJEC will share the full details, but appeals can now be made where there is 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.
“There is a guarantee that no-one will receive a lower grade after appeal and all appeals are free.”
Wales' education minister defended this year's A-level results, amid mounting criticism that students have been "short-changed" by a controversial grading system.
Exams were cancelled across the UK due to the coronavirus lockdown, with students instead being given A-level grades estimated by their teachers. But thousands of results deemed "optimistic" were subsequently adjusted down by moderators in a process known as standardisation.
A total of 42.2% of pupils were downgraded during the process which has left many frustrated and upset, with calls for an urgent review.
Adam Price, Plaid Cymru leader, said: "Pupils who were awarded lesser grades than the teacher assessments in A-level and AS exams should be upgraded to the teacher assessment grades.
"If this approach is being advocated by the UK Labour leader in England, why is the Labour First Minister in Wales so stubbornly against?"
"Further, this should be used as the mechanism for awarding GCSE results and this should be communicated to learners today for peace of mind."
Suzy Davies, the Welsh Conservative shadow education minister, said: "What we need now is urgent reassurance on time scales and a guarantee of two things.
"Firstly, all appeals affecting university or other higher education course places will be heard in time and that higher education institutions will keep open places until appeals are heard.
"Secondly, that this system will not collapse under the pressure of demand."
The Senedd's children, young people and education committee will be recalled on Tuesday and has invited the Welsh Government, Qualification Wales and WJEC to provide information and answer questions.
Committee chair Lynne Neagle said: "Given the significant concerns and complexities surrounding the awarding of exam results this year we will be meeting urgently to seek clarity for those who've been through this challenging process in unprecedented times."