Ok so does this mean I, as a small one man show business, cannot charge my customers interest on late payments? Must I register before I can charge them according to clause 4 and 5 (Incidental credit)?

Sorry I see this is an old thread, but some of my customers was "on a course" (June 2016) and apparently i may not allowed charge interest on overdue accounts if i am not registered? It is now "against the law"?