How to count major league service time?

 At first, no official information of each player's service time are shown, even on the player profile page of mlb.com. Each club's annual media guide provides service time of players who are on the 40-man roster or invited to spring training. As unofficial sources, several websites (FANGRAPHS, The Baseball Cube, BASEBALL REFERENCE, Baseball Prospectus, Cot's Baseball Contracts...) also provide. However, they do not necessarily cover every player (and......probably, sometimes incorrect). If we want to know service time of a player who are not covered by them, we are forced to calculate by ourselves based on the player's transaction history with dates sometimes uncertain......

General Rules

The calculation method of major league service time is shown in ARTICLE XXI of collective bargaining agreement. The summary is below...

• Service time is computed commencing with the date of the first regularly scheduled championship season game (the earliest opening day) through and including the date of the last regularly scheduled championship season game. Service time is not computed during spring training or any post-season games.
• One full day of major league service is credited for each day of the championship season a player is on major league active list.
• One full day of major league service is credited for each day of the championship season a player is on major league injured/disabled list, military list.
• One full day of major league service is credited for each day of the championship season a player is on paternity leave list, bereavement/family medical emergency leave list. (per Major League Rules MLR2(n, o))
• One full day of service is added if a player is on active or injured/disabled list for any tiebreaker game following the conclusion of the last regularly scheduled championship season game.    (note: this condition added for the first time in 2017-21 CBA, and at present, it was applicated only in 2018 season)
• A total of 172 days credited service will constitute one full year of credited service.
• A player may not be credited with more than one year of credited service, 172 days, in one championship season.

Specific Rules

 The calculation method under some specific situation is not shown in CBA or Major League Rules.

 I found out the below rules by examining the past actual transactions retrospectively, so most of them are not based on any official sources. Thanks to Arizona Phil's article from The Cub Reporter (TCR), which is the most detailed and comprehensive guide as far as I know, although as an unofficial source.

Exceptional Opening Day (International Openers)

If a player is on the active list, temporarily inactive list or injured/disabled list for any regular season game scheduled during spring training (known as "international openers" that may be scheduled in Australia, Japan, Mexico, etc), his service time is computed commencing with the date of his club's opening day instead of regularly scheduled opening day.

 

Optional Assignment

(Related post: How to count days on option? )

• If a player is optionally assigned for a total of 20 or more days in one championship season, 

• He shall not be credited with major league service during the period of such optional assignment(s). (per ARTICLE XXI-B of CBA)
• The date of optional assignment is counted as one day of service. (note: Arizona Phil says that it is NOT counted, but I do not think so)
• The date of recall is counted as one day of service. 
• If an optioned player is recalled not to report, the date of recall is not counted. 
• If an optioned player is recalled not to report and remained inactive, these days are not counted as any days of service.

(note: The date of optional assignment is counted not only as a day of major league service but also as a day on option, unless the assignment is taken place after the game) 

• If a player is optionally assigned for a total of less than 20 days in one championship season, 

• He shall be credited with major league service during the period of such optional assignment(s) (per ARTICLE XXI-B of CBA), including the date of optional assignment.
• The date of recall is counted as one day of service. 
• If he is recalled not to report and outrighted or remained inactive, the date of recall is not counted and his service time is interrupted on the previous day of the recall. 

A specific example: In 2016, Tim Beckham was optioned by Tampa Bay on May 25, recalled on June 1, optioned again on August 31 (post-game), and recalled not to report on September 11 (total of 18 days on option). He got 161 days of service counted from April 3 (the earliest opening day of 2016 season) to September 10, one day before he was recalled not to report. 

• If he is recalled not to report and designated for assignment or released, the date of recall is counted and his service time is interrupted on that day. 

A specific example: In 2019, Isaac Galloway was purchased by Miami on April 16, optioned on May 10 (post-game), recalled not to report and designated for assignment on May 24, and outrighted on May 29 (13 days on option). He got 39 days of service counted from April 16 to May 24, the date he was recalled not to report.

• If he has zero days of major league service in the current season prior to the optional assignment and after the optional assignment was unconditionally released or assigned outright and not subsequently added to the active list for the remainder of the championship season, he shall not be credited with major league service. (per ARTICLE XXI-B of CBA) 

A specific example: In 2015, Charles Brewer was optioned by Cleveland on March 17, recalled not to report and released on April 12. His option days were 8, counted from April 5 (the earliest opening day of 2015 season) to April 12, but he got no major league service because he had zero days of service before and after his option period. 

 

Outright Assignment

• If a player is outrighted, he shall not be credited with major league service during the period of such outright assignment(s).
• The date of outright assignment is counted as one day of service. 
• The date of reacquisition (purchase) is counted as one day of service.
• Even if a player is outrighted but reacquired within less than 20 days in one championship season, he shall not be credited with major league service during the period of such outright assignment(s), unlike the case of optional assignment.

 

Designated for Assignment

• If a player is designated for assignment, he shall be credited with major league service during the period of such status, through the actual assignment date (traded, released, outrighted, claimed on waivers or optioned). (per ARTICLE XIX-G of CBA)
• If a player is designated for assignment during spring and the actual assignment date is into the championship season, he shall be credited with major league service from the earliest opening day through the actual assignment date, even if he is never placed on the active list in that season. (note: Arizona Phil says that it is NOT credited, but I do not think so.)

A specific example: In 2016, A.J. Jimenez was designated for assignment by Toronto on March 28, and outrighted on April 7. He got 5 days of major league service counted from April 3 (the earliest opening day of 2016 season) to April 7, despite he was never on the active list during 2016 season.

• If an optioned player recalled not to report and designated for assignment, he shall not be credited with major league service during the period of such status. (note: Arizona Phil says that he is CREDITED, but I do not think so.)

 

 Restricted List, Disqualified List, Voluntarily Retired List

• If a player is placed on restricted or disqualified or voluntarily retired list, he shall not be credited with major league service during the period of such status.
• The date of placement is not counted as one day of service.  (I'm not confident, but maybe so)
• The date of reinstatement is counted as one day of service.
• Before the 2017 season, if a player was placed on restricted list as the result of a suspension for violation of the MLB-MLBPA JDPTP or a suspension or leave of absence related to a violation or possible violation of the MLB-MLBPA JDV policy, he was credited with major league service during the period of such status. However, if an optioned player was placed on restricted list as the result of such suspension, he was not credited with major league service.

 

 Trade, Claim on Outright Assignment/Trade Assignment Waivers

• If a player is traded to another major league club and activated immediately, his service time is not interrupted.
• If a traded player is not activated by the new club immediately, his service is interrupted on the day of trade, and restarts on the day he is actually activated.  (I'm not confident, but maybe so)
• If an optioned player recalled not to report and traded to another major league club, the date of trade is not counted, unless he is added to new club's active roster immediately.
• If a player is claimed on outright assignment or trade assignment waivers by another club, his service time computed as same as he is traded.

 

 Unconditional Release

• If a player is released, the date of release is counted as one day of service, and his service is interrupted on that day.
• If a released player is claimed on unconditional release waivers by another club and he accept, his service restarts on the day of waiver claim, unless he is not activated by the new club immediately.