@AZjoe - that is a very old post and some of the tax rules have changed since then.
There are two taxes: a) income tax and b) Self Employment (SE Tax).
The standard dedution is used to reduce your income BEFORE determining your "income tax".
The SE tax is based on your self-employed income and is NOT reduced by the standard deduction. Look at Schedule SE and it will show how the SE tax was calculated. That same number is then carried over to Line 23 of Form 1040.
