Your current Handicap index is based on your best 8 scores from your last 20 qualifying rounds. When playing at home you are allocated a course Handicap based on this > Course Handicap Table.
For those still reading:
When playing at an away Course your Handicap will change as per their Course Handicap Table. If it’s a casual round it will be the full allotted course Handicap and if it’s in a Stableford/Strokeplay Competition you will receive 95%
I know this is all very confusing for us all, but it will bed in over time.
Brian Cruise, Handicap Sec 2021 (slight amendment to wording, Stableford explanation deleted, Congu guide added 3/5/2021)