It’s official: MLB will be using the ABS challenge system throughout the entire 2026 season.
Robot umpires — also called “automated balls and strikes” (ABS) — have been used in the minor leagues and during the 2025 MLB All-Star Game, and now the system will come into full effect in the major leagues. While human plate empires will call balls and strikes, teams can challenge two calls per game and get additional appeals in extra innings.
The challenge system will be used for all spring training, regular season and postseason games beginning in 2026. Here’s what to know about ABS before it becomes a MLB mainstay.
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What does ABS stand for?
ABS stands for “automated balls and strikes”. The technology is powered by T-Mobile’s 5G Network.
MLB robot umpires, explained
ABS was tested in the minor leagues in 2021 and was implemented in 2022. It didn’t make its way to the majors until spring training in 2025.
Starting in 2026, the MLB will implement the same rules it used for ABS in spring training and for the 2025 All-Star Game. Each team will start the game with two challenges each. After a pitch and the subsequent call from the umpire, only the pitcher, catcher, or batter who is in the box may challenge the call. To do this, they will signal by tapping the top of their cap or helmet. The challenge signal must also be given immediately, not after receiving intel from coaches or teammates in the dugout.
BREAKING: Major League Baseball will officially introduce its ABS (Automated Ball-Strike Challenge System) for the 2026 season 👀
⚫️ Two challenges per team
⚫️ Can only be initiated by the pitcher, catcher or batter
⚫️ No one in the dugout or rest of the field can give input pic.twitter.com/WQEER0tuWv— The Sporting News (@sportingnews) September 23, 2025
The umpire will call time, and the pitch will be reviewed on the video board with the correct call. If the challenge is successful, it will be retained. If the challenge is not successful, it will be lost and deducted from the two challenges that the team began the game with.
COMING SOON: The Automated Ball-Strike Challenge System (ABS) presented by @TMobile will be used during Spring Training games for the first time ever.
ABS has been tested in the minor leagues since 2021, and 2025 will be the first test with the Major League players. About 60% of… pic.twitter.com/8Nc91IBfyc
— MLB (@MLB) February 20, 2025
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What is ABS?
ABS makes it sound like there won’t be an umpire behind home plate, instead giving way to an automatic call made after every pitch. While we may get there one day, that isn’t the case.
The first two instances of the ABS Challenge System occurred in today’s Cubs-Dodgers game.
We saw both a call overturned and confirmed. pic.twitter.com/2cIXlK6lc2
— MLB (@MLB) February 21, 2025
As seen in 2025 spring training and the All-Star game, ABS is just a challenge system where the pitcher, catcher or batter will be able to challenge two pitches during the course of the game. If they win the challenge, their team keeps the challenge. If not, they lose it.
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When did ABS begin?
The MLB has been testing ABS in the minor leagues since 2021. It has been implemented in some fashion in the lower levels since 2022. After repeated success, ABS made its way to the major leagues for the first time during the 2025 spring training, and it was used at the 2025 MLB All-Star Game.
Beginning with the 2026 season, the ABS system will be in use for every MLB game at every ballpark, per the MLB.
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ABS rules for 2026
The ABS rules for the MLB regular season and postseason will be largely the same as what has been used during its previous limited trials in the big leagues.
Here’s a MLB rundown of the system that will be a pillar starting in 2026:
- The ABS system will be in use for every MLB game at every ballpark for both the regular season and postseason
- Each team will start the game with two challenges apiece
- Only the batter, the pitcher or the catcher can challenge an umpire’s call
- Challenges must be made immediately after the umpire’s call, without assistance from the dugout or other players
- To challenge the call, a player will tap his cap or helmet
- For review, an animated pitch result graphic is shown to those in attendance on the video board and to home viewers on the broadcast
- A team only loses a challenge if the umpire’s call is confirmed (the challenge is unsuccessful)
- If a game goes into extra innings, any team that starts the extra inning out of challenges will get one challenge for the 10th inning
- If they exhaust that challenge, they will then get another challenge for the 11th, and so on
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How many challenges do teams get?
Each team will begin the game with two challenges apiece. When a pitcher, catcher, or batter challenges a pitch call, one of the team’s challenges will be used. If they are successful in their challenge, it will be retained. If they aren’t and the umpire’s call was correct, the team will lose that challenge.
If a game goes to extra innings and a team is out of challenges, that team will be granted an extra challenge for the 10th inning; if that challenge is exhausted in the 10th inning, they are granted one for the 11th, and so on.
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Who can initiate a challenge?
Only the hitter, pitcher or catcher can initiate a challenge, and it must be done immediately after the umpire’s call.
The player cannot get assistance from others, including those in the dugout.
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Will MLB umpires be used in 2026?
Yes, there will still be MLB umpires used in 2026. When testing the system in the MiLB, fans and players still wanted a human element in umpiring. Moreover, pitch framing would go away with ABS, which the majority of players do not support.
Per the MLB release, “The Challenge System is seen as a way to get more of the most important calls correct without dramatically altering the sport overnight. It is a middle ground between full ABS and tradition.”
The only thing that changes is that some of the umpire’s calls can be challenged. They will still be behind home plate, will rule on pitches, and will also be on hand for any plays at the plate.
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