The short answer
You no longer need to join a club for an official handicap. In England, iGolf gives you a full WHS Handicap Index for a small annual fee, with equivalents across Britain and Ireland, GHIN-linked options in the United States, and Golf Australia down under. Use one of those for the official record, and a tracking app for the day-to-day experience.
What an official handicap actually is
An official Handicap Index is one held and maintained by a body authorised under the World Handicap System. That authorisation is the difference between a number you calculate for yourself and one that clubs, counties and tournaments will accept. The good news is that authorised bodies now offer non-member options in most major golfing countries, so the barrier is a small annual fee rather than full club membership.
Great Britain and Ireland
England: iGolf
England Golf's iGolf subscription gives you an official WHS Handicap Index without belonging to a club, for a modest annual fee. You submit scores played under the Rules of Golf with a marker, and you get a genuine, portable index. It is the simplest route for an unattached golfer in England.
Wales, Scotland and Ireland
Wales Golf and Scottish Golf run comparable independent membership schemes, and in Ireland the GUI and ILGU structure handicapping for affiliated golfers. The principle is the same: an authorised body holds your record so your index is recognised.
United States
In the US the Handicap Index is administered through the USGA's GHIN system, accessed via an authorised golf association or club. Many state and regional associations offer membership that includes a GHIN handicap without requiring you to belong to a specific course, which is the American equivalent of the iGolf idea.
Australia and elsewhere
Golf Australia provides official handicaps through affiliated clubs and social or community memberships, linked to the national GOLF Link system. Most WHS countries now have some non-traditional membership route; if you are outside the regions above, your national golf federation's website is the place to confirm the local option.
Know your number while you sort the official record
Track every round to WHS rules from day one.
Tracking alongside your official index
An authorised body holds your official index, but the experience of those services is usually bare. That is where a tracking app earns its place. Golf Handicapp calculates your handicap to the same WHS rules, reads your scorecard from a photo, covers more than 24,000 courses, and shows the trend behind the number, so you understand it rather than just receive it. Run the app for the golf, an authorised body for the paperwork, and check any round instantly with the free calculator.