The Campeonato Nacional Seniores, to give the competition it’s full name, is split into 8 geographical divisions – Série A to Série H. At the end of each season, the top 2 clubs from each division are put into the Norte (north) or Sul (south) divisions.
The winners of the Norte and Sul divisions then take part in a grand final play-off game on a neutral ground. Both sides are promoted to the Liga 2 but the winner of this game is crowned the CNS Champion. Meanwhile, the two clubs who finish second in the Norte and Sul divisions play-off against each other home and away. The winner over two legs is promoted to the Liga 2.