Post-Season Roster Eligibility

A club's Post-Season Eligibility List is established at midnight (Eastern) on August 31st.
CoViD-19 EXCEPTION: A club's 2020 Post-Season Eligibility List will be established on September 15th.  

A club's Active List (26-man roster) must be submitted to the MLB Commissioner prior to the start of the first game of each post-season series (Wild Card game, LDS, LCS, and World Series).
CoViD-19 EXCEPTION: The post-season Active List roster limit will be 28 in 2020.  

A club's Active List can be changed (tweaked) prior to the start of the first game of each series (WC, LDS, LCS, and WS). 

1. A player who received a suspension for violation of the MLB-MLBPA Joint Drug Prevention and Treatment Program (player tested positive for a prohibited substance) prior to the start of Spring Training, during Spring Training, during the regular season, or during a post-season series (Wild Card, LDS, LCS, or World Series), is ineligible to play in any MLB or minor league post-season game(s) or series in that season, even if the player has completed serving the suspension. 

2. Any player on the Disqualified List, Ineligible List, Voluntary Retired List, or Restricted List (for any reason other than being placed on Administrative Leave pending investigation of a possible violation of the MLB-MLBPA Joint Domestic Violence, Sexual Assault, and Child Abuse policy or extended Bereavement/Family Medical Emergency Leave) as of midnight (Eastern) on August 31st or who is placed on the Disqualified List, Ineligible List, Voluntary Retired List, or Restricted List anytime after midnight (Eastern) on August 31st is ineligible to be included on a Post-Season Eligibility List that season. 
CoViD-19 EXCEPTION: A club's 2020 Post-Season Eligibility List is established at midnight (Eastern) on September 15th. 

3. All other players on a club's MLB Reserve List (40-man roster), MLB 60-day Injured List, and Military List prior to midnight (Eastern) on August 31st are automatically placed on a club's Post-Season Eligibility List and are eligible to be included on a post-season series Active List (26-man roster), but a player on an MLB 60-day Injured List who otherwise would be eligible to be included on a Post-Season Eligibility List is NOT eligible to be included until the player has spent at least 60 days on the Injured List, and a player on the MLB 60-day Injured List is NOT eligible to play in a post-season series until the player has spent at least 60 days on the Injured List AND the player has been reinstated from the 60-day Injured List.
CoViD-19 EXCEPTION: A club's 2020 Post-Season Eligibility List is established at midnight (Eastern) on September 15th. 

4. A player on a Post-Season Eligibility List at midnight (Eastern) on August 31st must remain on his club's MLB Reserve List, MLB 60-day Injured List, and/or Military List continuously throughout the remainder of the MLB regular season and post-season in order to be automatically included on his club's Post-Season Eligibility List. If a player is sent outright to the minors after midnight (Eastern) on August 31st, he is no longer automatically eligible to be included on a Post-Season Eligibility List.
CoViD-19 EXCEPTION: A club's 2020 Post-Season Eligibility List is established at midnight (Eastern) on September 15th. 

5. A "27th player" (must be a catcher) may (with approval of the MLB Conmissioner) be listed on a club's Active List for the LDS, LCS, or World Series as a replacement for a catcher who is suffering from an acute concussion. The catcher who suffered the concussion would be eligible to return to his club's Active List after seven days (even if it is prior to the conclusion of the series) at which point the "27th player" (the extra catcher) must be deactivated.
CoViD-19 EXCEPTION: A 29th player (must be a catcher) may (with approval of the MLB Conmissioner) be listed on a club's Active List for the LDS, LCS, or World Series as a replacement for a catcher who is suffering from an acute concussion. The catcher who suffered the concussion would be eligible to return to his club's Active List after seven days (even if it is prior to the conclusion of the series) at which point the "29th player" (the extra catcher) must be deactivated.

6. A post-season eligible player who is placed on the Bereavement/Family Medical Emergency List or on the Paternity List during a post-season series can (with approval of the MLB Commissioner) be replaced by another player on the club's Post-Season Eligibility List (a pitcher must replace a pitcher and a position player must replace a position player, but it is not necessary for a catcher to replace a catcher, an infielder to replace and infielder, or an outfielder to replace an outfielder), as long as the absent player is reinstated after no more than seven days (for a player on the Bereavement/Family Medical Emergency List) or after no more than three days (for a player on the Paternity List). If the series ends before the player is reinstated, he will automatically be reinstated prior to the next series, even if he has not returned to his club. 
NOTE: The absent player is not eligible to be replaced during a series if the player is a pitcher who pitched at least four consecutive innings in a game sometime previous in the series unless at least three days have elapsed since that game.

7. An injured post-season eligible player can (with the approval of the MLB Commissioner) be replaced on his club's Post-Season Eligibility List by a player (regardless of position) who was on an Active List, Reserve List, 60-day Injured List, or Military List of a minor league affiliate from that organization prior to midnight (Eastern) on August 31st, or by a player who was on the club's MLB Reserve List (40-man roster), MLB 60-day Injured List, or Military List prior to midnight (Eastern) on August 31st but who was subsequently sent outright to the minors. (In the case of a player who is sent outright to the minors after August 31st, the player must remain on a Reserve List of a minor league affiliate from that organization continuously throughout the remainder of the MLB regular season and post-season in order to be eligible to replace an injured post-season eligible player).
CoViD-19 EXCEPTION: A club's 2020 Post-Season Eligibility List is established at midnight (Eastern) on September 15th. 

8. A minor league player who replaces an injured player on the Post-Season Eligibility List must have his contract selected and be placed on the club's MLB Reserve List (40-man roster) before he can be placed on the club's Post-Season Eligibility List. If the club's MLB Reserve List (40-man roster) is full, a player must be removed (traded, released, or sent outright to the minors) from the club's MLB Reserve List to make room for the replacement player. 
NOTE: A player cannot be placed on the MLB 60-day Injured List after the conclusion of the MLB regular season, so placing an injured player on the MLB 60-day Injured List during the post-season to make room on the club's MLB Reserve List (40-man roster) for a post-season minor league replacement player is not an option.

9. A post-season eligible player who is injured during a post-season series (LDS, LCS, or World Series) can (with the approval of the MLB Commissioner) be replaced during the series by another player on the club's Post-Season Eligibility List, or by a player who was on an Active List, Reserve List, 60-day Injured List, or Military List of a minor league affiliate from that organization prior to midnight (Eastern) on August 31st, or by a player who was on the club's MLB Reserve List (40-man roster), MLB 60-day Injured List, or Military List prior to midnight (Eastern) on August 31st but who was subsequently sent outright to the minors. (In the case of a player who is sent outright to the minors after August 31st, the player must remain on a Reserve List of a minor league affiliate from that organization continuously throughout the remainder of the MLB regular season and post-season in order to be eligible to replace an injured post-season eligible player). An injured player replaced during a post-season series is ineligible to be reinstated to his club's Active List (25-man roster) for the balance of that series and the next series (LCS or World Series). Also, a pitcher must replace a pitcher and a position player must replace a position player. However, it is NOT necessary for a catcher to replace a catcher, an infielder to replace an infielder, or an outfielder to replace an outfielder. 
NOTE: If the injured player suffered an acute concussion, the injured player is eligible to be reinstated to his club's Active List after seven days even if the next post-season series is still in progress.