taxes Providing assistance to taxpayers in completing tax returns Collecting all taxes due related to such returns Enforcement of tax laws through examination of returns and assessment of penalties Providing an appeals mechanism for federal tax disputes Referring matters to the Justice Department for prosecution Publishing information about U.S. federal taxes, including forms, publications, and other materials Providing written guidance in the form of rulings binding on the IRS for the public and for particular taxpayers The IRS maintains several Service Centers at which tax returns are processed. Taxpayers generally file most types of tax returns by mail with these Service Centers, or file electronically. The IRS also maintains a National Office in Washington, DC, and numerous local offices providing taxpayer services and administering tax examinations. Examination Tax returns filed with the IRS are subject to examination and adjustment, commonly called an IRS audit. Only a small percentage of returns (about 1% of individual returns in IRS FY 2008) are examined each year. The selection of returns uses a variety of methods based on IRS experiences. On examination, the IRS may request additional information from the taxpayer by mail, in person at IRS local offices, or at the business location of the taxpayer. The taxpayer is entitled to representation by an attorney, Certified Public Accountant (CPA), or enrolled agent, at the expense of the taxpayer, who may make representations to the IRS on behalf of the taxpayer. Taxpayers have certain rights in an audit. Upon conclusion of the audit, the IRS may accept the tax return as filed or propose adjustments to the return. The IRS may also assess penalties and interest. Generally, adjustments must be proposed within three years of the due date of the tax return. Certain circumstances extend this time limit, including substantial understatement of income and fraud. The taxpayer and the IRS may agree to allow the IRS additional time to conclude an audit. If the IRS proposes adjustments, the taxpayer may agree to the adjustment, appeal within the IRS, or seek judicial determination of the tax. Published and private rulings In addition to enforcing tax laws, the IRS provides formal and informal guidance to taxpayers. While often referred to as IRS Regulations, the regulations under the Internal Revenue Code are issued by the Department of Treasury. IRS guidance consists of: Revenue Rulings, Revenue Procedures, and various IRS pronouncements applicable to all taxpayers and published in