Oh yeah, the IRS has all these complicated worksheets for figuring estimated taxes too. But in my personal opionion (I've been self-employed for years) they are an absolute waste of your time and effort. If you just send the IRS (and the state if the state taxes personal income) at least 20% of your *gross* business earnings each quarter, then at tax time you'll be fine. If you project that your total household income from all sources will be more than $100,000, then you should send in 25% each quarter, as you'll most likely be in the higher tax bracket.
It's easiest to pay your FEDERAL quarterly taxes online each quarter at <a rel="nofollow" target="_blank" href="
http://www.irs.gov/direct-pay">http://www.irs.gov/direct-pay</a>. Remember to print and keep that receipt when you pay!
