Serie A, as it is structured today, began during the 1929–30 season. From 1898 to 1922, the competition was organised into regional groups. Because of ever growing teams attending regional championships, the Italian Football Federation (FIGC) split the CCI (Italian Football Confederation) in 1921, which founded in Milan the Lega Nord (Northern Football League), ancestor of present-day Lega Serie A. When CCI teams rejoined the FIGC created two interregional divisions renaming Categories into Divisions and splitting FIGC sections into two north–south leagues. In 1926, due to internal crises and fascist pressures, the FIGC changed internal settings, adding southern teams to the national division, ultimately leading to the 1929–30 final settlement.
The Serie A Championship title is often referred to as the scudetto (“small shield”) because since the 1923–24 season, the winning team will bear a small coat of arms with the Italian tricolour on their strip in the following season. The most successful club is Juventus with 36 championships, followed by AC Milan and Inter Milan with 19 championships. From the 2004–05 season onwards, an actual trophy was awarded to club on the pitch after the last turn of the championship. The trophy, called the Coppa Campioni d’Italia, has officially been used since the 1960–61 season, but between 1961 and 2004 was consigned to the winning clubs at the head office of the Lega Nazionale Professionisti.
In April 2009, Serie A announced a split from Serie B. Nineteen of the twenty clubs voted in favour of the move in an argument over television rights; the relegation-threatened Lecce had voted against the decision. Maurizio Beretta, the former head of Italy’s employers’ association, became president of the new league.
In April 2016, it was announced that Serie A was selected by the International Football Association Board to test video replays, which were initially private for the 2016–17 season, allowing them to become a live pilot phase, with replay assistance implemented in the 2017–18 season. On the decision, FIGC President Carlo Tavecchio said: “We were among the first supporters of using technology on the pitch and we believe we have everything required to offer our contribution to this important experiment
During the season, which runs from August to May, each club plays each of the other teams twice; once at home and once away, totalling 38 games for each team by the end of the season. Thus, in Italian football a true round-robin format is used. In the first half of the season, called the andata, each team plays once against each league opponent, for a total of 19 games. In the second half of the season, called the ritorno, the teams play another 19 games, once more against each opponent, in which home and away matches are reversed. The two halves of the season had exactly the same order of fixtures until the 2021–22 season, when an asymmetrical calendar was introduced, following the format of the English, Spanish and French leagues. Since the 1994–95 season, teams are awarded three points for a win, one point for a draw, and no points for a loss. Prior to this, teams were awarded two points for a win, one for a draw and none for a loss. The three lowest-placed teams at the end of the season are relegated to Serie B, and three Serie B teams are promoted to replace them for the next season.
As of 2022, Serie A is ranked as the fourth-best league by UEFA coefficient, therefore the top four teams in the Serie A qualify straight to the UEFA Champions League group stage. The team finishing fifth, along with the Coppa Italia winner (if the Coppa Italia winner finishes outside the top five) or the team finishing sixth (if the Coppa Italia winner finishes inside the top five), qualify for the UEFA Europa League group stage. The sixth or the seventh ranked club, depending on the Coppa Italia winner’s league performance, joins the final qualification round of the UEFA Europa Conference League.
If after all 38 games, there are two teams tied on points for first place or for 17th, the last safety spot, the team that wins the scudetto or stays up at 17th is decided by a single-legged play-off game of 90 minutes and penalties (no extra time), to be held at a neutral venue, with the host team decided by the tiebreakers listed below. If at least three teams are tied for one of those spots, then the two teams to play in the match is decided by a mini table between the teams involved using the tiebreakers below. The deciding tie-breakers for any ties on all other positions are as follows:
- Head-to-head points
- Goal difference of head-to-head games
- Goal difference overall
- Higher number of goals scored
- Play-off game at a neutral venue if relevant to decide European qualification or relegation; otherwise by coin flip
Between 2006–07 and 2021–22, the tiebreakers currently used for all places to decide the scudetto winner if necessary, though this was never needed. Before 2005–06, a play-off would immediately be used if teams were tied for first place, a European qualification spot, or a relegation spot. In some past years, the playoff was a single game at a neutral site while in others it was a two-legged tie decided by aggregate score. A playoff game has never been needed since the tiebreaking format changed.
The only time a playoff was used to decide the champion occurred in the 1963–64 season when Bologna and Inter both finished on 54 points. Bologna won the playoff 2–0 at the Stadio Olimpico in Rome to win the scudetto.Playoff games were used on multiple occasions to decide European competition qualifications (most recently in 1999–2000) and relegation (most recently in 2022–23).