(Taken from Golf Australia Website)

The Committee reviewed the amended regulations (which came into effect on 1 April 2009) relating to the handicapping of four-ball competitions.
With a view to achieving greater simplification, and to continue the process of aligning our systems with the determined forward direction, as well as to clarify the procedures in light of various queries, the following amended regulations were adopted:
Four-ball scores (including mixed events) MUST be used for handicapping an individual player but only if the following requirements are met:The pair has a score of at least 42 Stableford points (6 up in Par or net 6 under in Stroke events).
The individual player's score appears at least 9 times on the four-ball score card.
The adjusted score (after the below method has been followed to create an individual score card) will result in a reduction to the individual player's handicap.
(GOLF Link clubs will enter these scores as ad-hoc scores; the AMCR/AWCR is to be used in all cases.)
Note i – WHERE AN INDIVIDUAL PLAYER’S SCORE IS TO BE HANDICAPPED (irrespective of whether the competition is played as Par, Stroke, or Stableford), IT MUST BE PROCESSED AS A STABLEFORD SCORE in accordance with the procedures contained within this regulation.
Note ii – If two identical net scores are recorded by partners on a hole, both scores are eligible to be used on an adjusted individual score card. However, if the first player to hole out can be readily identified, the second player is deemed to have not recorded a score for that hole.

PROCEDURE FOR COMPLETING FOUR-BALL SCORE CARD:

When a player has no handicap stroke on a hole and their score is not recorded on the four-ball card, they are given 1 Stableford point.
On holes where a player receives 1, 2, or 3 handicap strokes and their score is not recorded on the four-ball card, they are given 1½ Stableford points.

When a player’s score is recorded on the four-ball card for a hole, they are given the appropriate number of Stableford points for that hole.

When all the gaps in the card have been filled in, the points should be added, and where a half appears in the total, the points total should be rounded to the next lower whole number.

The score obtained is recorded in the player’s handicap record sheet and treated in the same way as all singles scores for handicap purposes.