You have the right to challange the IRS and to be heard. If you've gotten a notice from the IRS and they say you owe them money, don't rush out and pay them because that is not the end of the discussion. You have a right to challenge what they say in their notice. They do give you a limited amount of time to respond, but you should respond. Carefully read over the notice, get advice if you need to, and then respond in the manner they ask. You can't just call them and say, "You got it wrong", because the IRS usually needs documentation to show why you believe the way you do. You need to substantiate the view you have taken.
You can get copies of records and written info on the tax code and fax or mail it to them. The IRS will consider your objections in a prompt and fair manner. Don't expect a fast response, but you will get a response. The IRS will respond either indicating they agree with you or that they disagree with your argument and why. There is a limited amount of time that you can argue with the IRS and they will always give you deadlines. DO NOT IGNORE THOSE DEADLINES!
The IRS is not there to "get you" or "steal your money". There is a tax code they must follow and you can disagree and point out where you think they are wrong. They will listen. Eventually there will be a final decision, one way or another. But that still isn't the end of your rights. The next "Taxpayer's Rights" post has to do with appealing the "final notice" of the IRS.