Have to agree with Ronny. I basically do the basic book keeping for our S/F and our trading company myself, to the extent possible. All the balancing etc. This usually alerts me to any missing info or problems, which I can get to the bottom of before the accountant gets confused and wastes time/money on it. This does reduce costs. It includes my trading to the extent that I can. This depends on the kind of files that I receive from my broker. Unfortunately, CBS does not give me excel files. However, my accountant seemed happy with what I gave them, even though to me, the CBS stuff was hard to reconcile.
Also, the other year I paid considerably larger fees when I used some products my accountant knew little about, including a managed fund with a warrant structure and other more conventional instalment warrants for market trading. Had to get legal advice to confirm it was all OK (it was, but my accountant AND auditor didn't know this). Going backwards and forwards with people who were so unfamiliar with this kind of product that they had to educate themselves at my expense was time consuming for all of us, and expensive for me. I did switch accountants after that. It's important and cheaper to have an accountant who is familiar with the kind of investing you do.