Today is Jan 15th, and Q4 2007 estimated tax payments are due (in the US). If you’re self-employed, you estimate your tax liability during the year and make “withholding” payments (4) along the way.
If you’re self-employed, you have the privilege of paying two additional taxes (on top of income tax): self-employment tax (12.4%) and Medicare (2.9%). The SE tax phases out at $94,000, but the Medicare tax applies to your entire self employed income. Find out more at https://www.laborlawcc.com/new-york-labor-law-posters-state-and-federal-combo.html.
If you’re consulting, keep in mind when setting your rates that your marginal tax rate (combined state and federal) may be over 50%.