These are excellent answers! And while this has been sitting on the board for awhile, for any new users I'd like to provide another perspective.

For about half if my clients that have never had bookkeeping before, my costs for the year are almost wiped out by the tax savings I discover for them (only considering base services, classifying, reconciling, chart of accounts, reports).

Also many clients I've taken on have mis-reported on their taxes due to bookkeeping errors. This may "flag" them for audit if the error is large enough. While some clients had errors that benefited them financially, others overreported by $10000 by misclassifying contributions as sales or other errors. Also, a bookkeeper can help track info for you. In a recent audit, a client lost $40k in legitimate expenses due to no documentation (receipts, bookkeeping), and there were also no 1099s sent out. These are big no-nos. This was for an audit of 2011, well before I was handed the books. The bookkeeper reduces your risk and can save you in an audit.

Finally, 90% of my clients have improved revenues once bookkeeping...so that now it more than covers base bookkeeping costs. Why? They see info monthly and presented to them. Initial reactions are beautiful. Clients are surprised, frustrated, encouraged, or any number of emotions, but at the end, they are motivated! They now have a "coach" with whom to discuss ideas. There is research to support that those that stay on top of their books grow faster.

Just like Suzette above, I do client bookeeping while looking to outsource my own. Why? I myself like to pay attention to my initial reaction to the reports and institute change! When I do my "own" books daily, I'm too into the minutiae and don't have the same reaction. Plus, I want to focus on my business, which is doing client books and developing new services to help them.