This document summarizes aspects of the Swiss social security system, U.S. taxation of foreign retirement plans, and bilateral agreements between the U.S. and Switzerland related to social security and taxation. The Swiss social security system has three pillars: compulsory old-age and disability insurance, compulsory occupational pension plans, and voluntary individual pension plans. The U.S. allows foreign tax credits for taxes paid to foreign countries and has rules for taxing deferred compensation plans. Bilateral agreements between the U.S. and Switzerland address taxation of pensions and social security benefits and allow certain foreign social security plans to be excluded from U.S. deferred compensation rules.