Members of Congress have demonstrated an ongoing interest in annual U.S. contributions to the United Nations (U.N.) regular budget, which funds core activities for U.N. organs such as the General Assembly and Security Council, staffing and administration at U.N. headquarters, international conferences, human rights promotion, and U.N. special political missions, among other things. Over the years, Congress has focused on the overall cost of the U.S. assessment to the regular budget per year, as well as any outstanding contributions; how the United States assessment compares to the assessments of other U.N. member states; and how the United States' payment of its assessed contributions over time compares with other U.N. member states. In 2010—the last calendar year for which data are publicly available—the United States was the single largest contributor to the regular budget, paying $532,435,102, or 22%, in assessed contributions. The next largest contributors were Japan (12.530%), Germany (8.018%), the United Kingdom (6.604%), and France (6.123%). Seventeen countries, including the United States, were assessed at over 1%, representing about 83% of the total regular budget. Ten countries were assessed between 0.5% and 1%, accounting for about 7% of the budget. The rest of the U.N. membership (167 countries) accounted for about 8% of the regular budget. This report highlights, for each of the past 20 years, payments and the total outstanding contributions of the top contributors to the U.N. regular budget—including the United States. For additional information on U.S. funding of the U.N. system, see CRS Report RL33611, United Nations System Funding: Congressional Issues , by [author name scrubbed]. The enclosed tables list the assessment level, actual payment, and contributions outstanding of key contributors to the U.N. regular budget from calendar years 1990 through 2010. Most countries pay their assessment in full during the calendar year. Other countries, however, (including Argentina, Brazil, Ukraine, USSR/Russian Federation, and the United States) have on occasion failed to pay the entire assessment and maintained unpaid or outstanding contribution balances. Consequently, the annual payments listed may not always match the assessment for any given year. Each table is divided into four columns, described below. Countries —Contributing countries are grouped into key categories: (1) the "United States"; (2) "Other Major Contributors," which are countries assessed at more than 1%; (3) "Middle Contributors," a new category created in 2004 that provides data on nations that are assessed at 0.5% and over but less than 1%; and (4) "Rest of Membership," which lists overall contributions from the remaining member states. Assessment —The percentage of the U.N. regular budget at which a country is assessed. Payment —Country payments to the U.N. regular budget that have been received and duly recorded as of December 31 of each calendar year (assessed contributions received after that date are reported in the next statement on the status of contributions). Contributions Outstanding —Total outstanding contributions represent money owed by a country as of December 31 of that year. It includes both current year and prior year contributions outstanding. Four of the five permanent U.N. Security Council members are identified in each table, and information on the fifth permanent Council member, China, is provided in a footnote. China is included among the major contributors starting in 2001, when its assessment level first exceeded 1%. 

Summary: The United States is the single largest contributor to the United Nations (U.N.) regular budget. As such, Members of the 113th Congress will likely continue to demonstrate an interest in the United States' assessment level, the cost of the U.S. assessment each year, how U.S. contributions to the regular budget compare to those of other countries, and how assessment levels have changed over time. This report provides the assessment level, actual payment, and total outstanding contributions for the United States and other selected U.N. member states from 1990 to 2010—the last year for which data are publicly available. In 2010, the United States was assessed to pay 22% (or $532,435,102) of the regular budget. The next largest contributors were Japan (12.53%), Germany (8.018%), the United Kingdom (6.604%), and France (6.112%). This report is updated annually, or as the U.N. document upon which the data are based is published.