Second quarter estimated taxes are due June 15. For self employed people, this is a big deal because they don't have paychecks with taxes withheld. We wrote a simple overview about making estimated tax payments last fall, but thought it would be worth spelling things out in a bit more detail.
When self employed people make their quarterly tax payments, they are actually sending in money for two different types of taxes: self employment taxes and income tax.
Let's started with self employment tax. To begin with, I've always found the use of the word "tax" to be a bit misleading here, since self employment "taxes" are actually your required contributions to Social Security and Medicare. But who are we to argue with the IRS and an entire industry? 
The Social Security tax rate for 2009 is 12.4% for every dollar earned, up to $106,800 (vs. $102,000 in 2008). The Medicare tax rate is 2.9% of all earnings.
The second part of a self employed person's estimated taxes is income tax. This is the same income tax everyone has to pay though, as stated above, because there's no withholding from paychecks, each quarterly bill can loom large.
Using Outright.com, you can find out exactly how much self employment taxes you owe on your business profits. We even provide an estimate of your income taxes owed (though, to be truly accurate, we'd require your entire personal tax situation and well... that's your business).
