A barrister is defined as a person who is qualified, or who has
a right, to plead at the Bar in a Court of Law. A newly qualified
barrister, unless exempted by his Inn of Court, must complete a
year's practical training (the pupillage period) during the first
six months of which he cannot accept instructions or conduct any
part of a case himself. The profession of barrister, therefore,
cannot in any event commence before the end of the first six months
pupillage. While the question of when the profession commences
thereafter is one of fact, the most likely date of commencement is
that on which the barrister is in a position to accept briefs and
has instructed the clerk to obtain such briefs.
You should assess any fees received prior to the commencement of the practice (for example fees from the writing of articles, etc.) under Case VI of Schedule D.
The profits of barristers were previously usually computed on a cash basis. The cash basis was abolished by FA98/S42 for periods of account beginning after 6 April 1999. There is detailed guidance at BIM74000+.
FA98/S43 permits a barrister to use the cash basis in the seven years following their first holding themselves out for work - there is guidance at BIM74020.