Andrew Kerth

The MLB postseason eligibility deadline is 11:59 p.m. ET on August 31 — not a roster deadline so much as an organizational one. What it actually requires.

The answer is two. MLB rosters go from 26 to 28 on September 1, and all 28 spots are mandatory — not optional as they once were.

Yes. Every day a September call-up spends on the active roster counts toward service time — and roughly 30 days can move a player’s free agency by a full year.

September call-ups usually keep rookie status for the following season — because the 45-day roster threshold deliberately excludes September. The two limits that still apply.

A September call-up earns the prorated MLB minimum — roughly $4,200 a day. For many players it’s the largest month of pay in their career by a wide margin.

MLB scrapped 40-man September rosters and capped them at 28. The reasons behind the change, what it fixed, and what fans lost.

September call-ups can play in October — but only if they were already in the organization by August 31. The deadline that decides it, and the one exception.

Every September call-up must already be on the 40-man roster. Why that single rule decides who gets promoted, and what teams do when the 40 is full.

Rosters expand from 26 to 28 on September 1. The prospects most likely to get the call, and why the two extra spots usually go to relievers rather than star bats.