Yes, in full. Every day a player spends on the active roster or the major league injured list accrues one day of service time, and September is no different from April.
A call-up who arrives on September 1 and stays through the end of the regular season banks roughly 30 days. That sounds trivial. It isn’t.
How the Clock Works
A full service year is 172 days, even though the regular season runs longer than that. Service time is expressed as years and days — a player with two years and 100 days is written as 2.100.
Six full years unlocks free agency. Three years usually unlocks arbitration, with a subset of players qualifying earlier through the Super Two cutoff.
Why 30 Days Can Be Worth Millions
Because the thresholds are cliffs, not slopes. A player at 5.171 is not almost a free agent — he is a full season away. One day short of 172 means the entire year doesn’t count.
So a September call-up’s 30 days can be the difference between reaching free agency after six seasons or after seven. That seventh year of club control, at a salary far below market, is routinely worth tens of millions to a franchise.
It is the reason clubs think carefully about promotion dates, and the reason the practice has generated so much friction between the league and the union.
What Counts and What Doesn’t
| Status | Accrues service time? |
|---|---|
| On the active roster | Yes |
| On the major league injured list | Yes |
| Optioned to the minors | No |
| On the 40-man but in Triple-A | No |
Note the second row. A player who gets hurt in September still accrues service time on the major league injured list, which is why an injury after a call-up doesn’t cost him the clock.
The Prospect Promotion Incentive
The 2022 CBA introduced a counterweight. Under the Prospect Promotion Incentive, a club that carries a top-ranked prospect on its opening day roster can earn a bonus draft pick if that player finishes highly in award voting.
The idea is to make promoting a prospect early worth something, rather than leaving clubs with a purely financial reason to wait. It has changed some behaviour, though the underlying incentive to manage the clock hasn’t gone away.
Rookie Status Is Separate
Service time and rookie eligibility are different systems. September days count fully toward service time but are excluded from the 45-day threshold that governs rookie status.
So the typical September call-up finishes the year with about 30 days of service time and his rookie eligibility intact. Full detail on the mechanics is in our service time explainer.
The Bottom Line
Yes, September call-ups accrue service time at the normal rate — one day for every day on the active roster or major league injured list. Roughly 30 days from a September promotion can eventually decide whether a player reaches free agency after six seasons or seven, which is why those days are worth far more than they look.