As of the 1st of April 2024, 4BBB scores that meet the below criteria can qualify as a handicap card.

Pre 1st of April 2024

Acceptable Scores for Handicap Purposes

All 9 hole and 18 hole Singles Competition Rounds in Authorised Formats must be submitted for handicap purposes, subject to the competition being played to the Rules of Golf and over the measured length of the course
Scores from team competitions and match play will not be acceptable in England initially, although this may change based on feedback from other jurisdictions that include those formats
The recommendation from England Golf is that scores from regular organised social events (roll-ups) in authorised formats are submitted

Pre-registration

Players are required to register their intention to submit a score from general (non-competition) play before commencing the round
This is similar to the arrangements for Supplementary Scores under the current system

Minimum Number of Holes

Scores may be submitted over 9 holes or 18 holes.
All 9 holes must be played to submit a 9 hole score. The scores are scaled up to an equivalent 18 hole score by adding Net Pars for the remaining holes plus one additional stroke, or 17 points in Stableford format.
An 18 hole score will count as long as 10 or more holes have been played.  Holes not played are recorded as Net Par or (Net Par + 1), depending on the number not played. 

Adjusted Gross Score

For handicap purposes a big score on any hole is reduced to Net Double Bogey, using the player's Course Handicap. Holes started, but not completed are also recorded as Net Double Bogey

Score Differential

The Adjusted Gross Scores is compared with the Course Rating and is "de-sloped" to give the Score Differential for the round, which is added to the player's Scoring Record

Playing Conditions Calculation (PCC)

Determines if course and weather conditions on the day differed from normal to the extent that they significantly impacted players' performance.
Calculated using all scores submitted on the course that day, as long as 8 or more golfers with a Handicap Index of less than 36 and a fully developed Scoring Record  played.
It is conservative in nature and can increase the Adjusted Gross Score by 1 in easy conditions or decrease it by 1, 2 or 3 in difficult conditions.

9 Hole Scores

A 9 hole Score Differential is calculated as:

= [ 113 / 9 hole Slope Rating ]  x  [ 9 hole Adjusted Gross Score - 9 hole Course Rating - (0.5 x PCC) ]