Please refer to the CA website for definitive details of the new system.
The upper and lower handicap limits have been removed. It would appear that handicaps lower than -6 and higher than 20 are not expected, but under the new arrangements there is nothing to prevent this.
In order to accommodate the extension of allowed handicap values, all players with an existing Golf Croquet handicap will have their indices increased. The table of trigger points has been amended accordingly. Most players will retain their existing handicaps. Players with handicaps of 2 or less may have a change on a rule based rather than subjective basis. Players struggling on a handicap of 12 may have their handicaps adjusted by the club handicapper to a higher value.
The contentious notion of Effective Handicaps for players on 3 or less has been abandoned.