A week ago I wrote that a player's free agency could be delayed a year by calling him up on April 11th or later, making it impossible for him to accrue more than 171 days of service time. It turns out that I was only partially correct.
The April 11th date only applies if the player is not on the 40-man roster right now. For example, Brandon Belt could be promoted by the Giants on April 11th or later and his free agency would be delayed until after the 2017 season, because he is not currently on the 40-man. One related note - if he was called up exactly on that date, and thus fell one day short of the 172 needed for a year of service, his agent would probably file a grievance. There's also the possibility of a one-game playoff allowing him to pick up that extra day of service time anyway. So it makes sense to leave a little space.
What about a player who is on the 40-man roster, such as the Orioles' Zach Britton? In that case, the player needs to be optioned to start the season and spend at least 20 days on optional assignment in order to not get the service time back. So a 40-man roster player can earn either 162 or fewer days of service, or a full year. The Orioles will have to wait until April 21st or later with Britton, as Dan Connolly of the Baltimore Sun indicated today.