For example, let's say that you've contributed $25,000 to your Roth IRA, have never made a withdrawal, and your balance is now $35,000, including investment profits. If you withdraw $30,000 prematurely, $25,000 of that amount is tax-free since it represents your original contributions. The remaining $5,000 of the withdrawal will be considered taxable income.
If you have any other questions about IRAs that we haven't covered here, take a look at our IRA Center. We can help you make the decisions that work best for your situation.