Taxes and Solo Law practice: Yes, you have to pay.

In case you didn’t already know this, I’ve got some bad news: small business owners have to withhold and pay their own taxes. Solo attorneys are considered self-employed, which means you need to pay estimated taxes throughout the year, or take a penalty and write a big check at the end of the year (disclaimer: I am not an accountant or a tax attorney).

article here. From the Lawyerist- a good series of articles on the business aspect of running a solo or small practice.