The World Handicap System was introduced in Great Britain & Ireland on 2nd November 2020. From that date your handicap is based on the average of your best 8 scores from the last 20 rounds. The main features of the system are described below.
Course Rating replaces Standard Scratch (SSS) and represents the score that a scratch golfer is expected to achieve on the course.
Slope Rating is the relative difficulty of a course from a specific set of tees for a bogey golfer compared to a scratch golfer, as described on the Course & Slope Rating page.
Singles Competition Rounds and Social Scores in Authorised Formats may be submitted for handicap purposes, as described on the Acceptable Scores page.
A measure of a player’s demonstrated ability calculated against the Slope Rating of a golf course of standard playing difficulty, as described on the Handicap Index page.
Course Handicap is the number of handicap strokes a player receives (before Handicap Allowances), on a specific course and a specific set of tees.
Playing Handicap is the Course Handicap adjusted for any Handicap Allowances. It represents the actual number of strokes the player gives or receives for the round being played.
See the Course & Playing Handicaps page.
The WHS introduced a number of new terms as described on the Definitions Page.
Click Here for the Players Guide to WHS from England Golf.
It is a good summary (it is meant to be a printed document – please ignore the printers marks!)
From England Golf: WHS Frequently Asked Questions
and a series of short videos on specific aspects of the system on YouTube