When calculating a differential in which the gross score is less than the USGA Course Rating, you will get a negative number.  With enough of these "minus handicap differentials " (see 10-1b) used for the Handicap Index calculation, the result becomes a plus Index.

For notation purposes, the resulting Handicap Index is labeled with a "+" sign.  This corresponds to the number of strokes you are giving back to the golf course (see Course Handicap ).  It is strictly for notation purposes and does not affect the Handicap Index calculation.