Golf has a single set of playing Rules, a single set of equipment Rules and a single set of Amateur Status Rules overseen by the USGA and The R&A. Yet, today there are six different handicap systems used around the world, each of the different systems producing slightly differing results. To unify all six systems into a single system, the USGA and The R&A developed the World Handicap System which calculates handicaps for all golfers around the world.
The WHS is expected to be implemented in the United States in January 2020. In order to transition to the World Handicap System the player’s current handicap system must be reprocessed using the WHS principles. For this reason, it is very difficult to predict how a player’s handicap index might change under the WHS. Some players might stay the same while others might go up or down by 2 or 3 strokes. So, if you notice that your Handicap Index is different in January despite not having played, this is why!