Articles Regarding IRS Audit Process:

DORA's Landowner Protection Tips

How to Deal With (And Survive) I.R.S. Income Tax Audits
Colorado Bar Association, Taxation Law Section, Tax Brochures
This brochure is in a question and answer format and provides information intended to help individual taxpayers better understand how the IRS and the Colorado Department of Revenue determine and collect taxes.
http://www.cobar.org/group/display.cfm?GenID=469

Letters and Notices Offering an Appeal
Internal Revenue Service
This document explains the different letters and notices a taxpayer can receive from the IRS.

Notice of Deficiency
Internal Revenue Service, United States Department of the Treasury
This article explains the procedures a taxpayer should follow when he/she receives a notice of deficiency from the IRS.

EP Examination Process Guide - Section 7 - Appeals - Statute Protections
Internal Revenue Service
This document explains the statute of limitations for the IRS for assessing taxes and making refunds or credit of tax. This also explains how the IRS can ask a taxpayer for an extension and what happens when the taxpayer grants or denies the extension. There are links to other documents from this article including extension forms and Extending the Tax Assessment Period, an IRS publication that explains extensions in more detail.

Your Appeal Rights and How to Prepare a Protest if You Don't Agree
Internal Revenue Service, Publication 5
This publication explains how the procedure of appealing a tax case if the taxpayer does not agree with IRS findings. It also covers the procedure to take the case to Tax Court, District Court, and Court of Federal Claims.

For more information about the IRS Appeals Process, go to this link.

Articles Regarding Colorado Department of Revenue:

FYI - For Your Information: Statute of Limitations
Colorado Department of Revenue, Taxpayer Service Division
This document explains the statute of limitations for Colorado income tax refunds and assessments. The statute of limitations is the time period during which a person may file a claim for a refund, an assessment or audit may be initiated, or a collection activity may occur. It also explains when the statute of limitations can be extended.

Appeals Procedures for Audit Adjustments and Refund Denials
Colorado Department of Revenue
This document explains the procedure that a taxpayer must follow if he/she wishes to protest a notice of proposed audit adjustments or the denial of a refund. Once a taxpayer gets notice that his/her tax return is being adjusted as the result of an audit, he/she has 30 days to send in a written application for a hearing.

What is the 30-Day Rule?
Colorado Department of Revenue
This article explains that when a taxpayer receives a notice of deficiency, he/she has 30 days to pay the tax or protest the notice of deficiency.