PGA Tour members commit to playing in a minimum number of tournaments on the schedule each year, showing support for the organization and their fellow members. Beginning in the 2016-17 season, however, the rules were slightly tweaked in hopes of bolstering tournament fields each year.
For years, the minimum number of events a PGA Tour player must compete in each season has been 15, including official events, as well special events like the Olympic golf tournament, the Ryder Cup and Presidents Cup. However, that rule has since been altered to include a caveat.
If a regular member, meaning those who don't have lifetime membership status (having 20 PGA Tour wins and a minimum of 15 years on the PGA Tour), veteran status (being at least 45 years old in the current season) or dual PGA Tour-PGA Tour Champions membership, then they have to add an event to their schedule each season they hadn't played in the prior four seasons. Unofficial events like the Presidents Cup and Ryder Cup count toward the tournament tally, but a player needs to add a new event to their schedule, provided they plan on playing less than 25 tournaments that season.
A number of PGA Tour-recognized events cannot satisfy the new-event requirement, including the four majors, The Players, the four World Golf Championships events, the FedEx Cup playoff events, the Ryder Cup, the Presidents Cup and any first-year official-money event.
If a regular PGA Tour member plays in 25 or more events in the immediately prior or current season, then they don't have to add a new tournament.
If a regular PGA Tour member doesn't play in 25 or more tournaments in the immediately prior or current season AND doesn't add an event they haven't played in the prior four seasons, then that player is subject to a three-tournament suspension and a major fine of at least $20,000.
The policy is designed to exempt lesser players who are often ineligible for the majors, The Players, World Golf Championships and may barely get into the FedEx Cup playoffs. It's also designed to make it easy for a better player to set a more compact schedule, provided they help out the Tour and its tournaments by competing in a new event.
It's a win-win.