During the past 6 years, GAO, the Internal Revenue Service (IRS), and others have cited delayed, inaccurate, incomplete, and confusing responses to taxpayer letters as chronic IRS problems. Although IRS has made progress in correcting its correspondence problems by adopting quality and timeliness standards and by expanding quality reviews of outgoing mail, some problems persist. A GAO review of nearly 1,900 closed correspondence cases in IRS' Atlanta and Cincinnati service centers found that 15 percent of the cases were incorrect, unclear, incomplete, or nonresponsive. Also, 11 percent of the cases resulted from taxpayers repeatedly trying to contact IRS to resolve a matter. Problems such as these increase IRS' costs, frustrate taxpayers, and ultimately discourage taxpayer compliance with the tax laws. GAO outlines several opportunities for IRS to improve its responsiveness to taxpayers, including resolving more taxpayer issues by telephone, clarifying the situations that warrant an IRS response to taxpayer correspondence, making timeliness indicators more useful, and improving interim letters.