The final game of the Spanish Super Cup is usually tight, as both teams use more defensive power than anything else. But in case the game ends in a tie during the first ninety minutes the game will go to extra time for both teams to try to win the game. That is the first part of the solution in case the game ends in a tie, but in case the extra time also ends in a tie, the winner will be decided on penalties.
In the last two editions of the Spanish Super Cup the winner was decided in extra time and penalties, but with the previous format where both teams played two legs, more than 7+ ties were played, although extra time or penalties were never necessary.
Athletic Bilbao and FC Barcelona played in the 2020-21 Super Cup final, that game ended in a 2-2 draw, but in extra time, Athletic Bilbao was more dominant and they scored a goal to avoid the penalty round.
What happens if there is a tie in the Spanish Super Cup?
If the 90' minutes of the game, including injury time, end in a tie, both teams will have to play extra time to try to win the game in two halves of 15 minutes each. But if neither team scores a goal to win in extra time, then the Spanish Super Cup final winner will be decided on penalties.
The only time in the history of the Spanish Super Cup that the winner was decided on penalties was during the 2019-20 season since with the new format the tournament is played in a single leg and not two legs as was done until 2017. In 2019-20 Real Madrid drew against Atletico Madrid 0-0 and the extra time was also a 0-0 draw, but Real Madrid won 4-1 on penalties.