My wife recently began working again follwing the birth of our first child. She is a Licensed Clinical Social Worker and had been employed by the Commonwealth of Massachusetts until the little guy came along. She recently began working again, "independently contracting." She did adoption case evaluations for which she was paid a fixed amount for each report. She is about to receive her first compensation check, and since she acts as an independent contractor, she will be paid the gross amount: no payroll taxes or social security are taken out. This is where I'm in the dark, and after stumbling through the IRS web site for help, I'm hoping someone here might be able to offer tax advice. Specifically: I know I am supposed to pay estimated taxes for her on a quarterly basis, or be subject to severe tax penalties. What forms should I be using? Do I have 30 days from the end of each quarter to pay the estimated tax(es)? How can I compute the amount? Is it true that she has to pay social security twice: once as an employer and once as the company's sole employee. What else am I missing? Thanks in advance, Thos.