Definition and Mechanics of Zero-Coupon Bonds
A zero-coupon bond is a debt instrument that makes no periodic interest (coupon) payments and is instead issued at a price below its face value - hence the alternative names 'discount bond' or 'deep-discount bond.' The investor's return comes entirely from the difference between the purchase price and the face value received at maturity.
For example, purchasing a zero-coupon bond with a face value of 1 million yen for 800,000 yen and receiving 1 million yen at maturity in 10 years yields a profit of 200,000 yen, equivalent to an annualized yield of roughly 2.26%. U.S. Treasury STRIPS (Separate Trading of Registered Interest and Principal of Securities) are among the most widely known zero-coupon bonds, used by both institutional and retail investors.
Comparison with Coupon-Bearing Bonds
Conventional coupon bonds pay interest semi-annually or annually, whereas zero-coupon bonds generate no cash flow until maturity. This characteristic gives zero-coupon bonds a higher sensitivity to interest rate changes (duration) than coupon bonds of the same maturity. If interest rates fall by 1%, a 10-year zero-coupon bond rises roughly 10% in price, while a 10-year coupon bond (3% coupon) rises only about 8.5%.
A key advantage of zero-coupon bonds is the absence of reinvestment risk. With coupon bonds, the investor must reinvest received interest, and if rates have fallen, the reinvested income earns less than expected. A zero-coupon bond held to maturity locks in the yield established at purchase, making it well-suited for funding known future obligations such as education expenses or retirement.
Tax Considerations and Common Misconceptions
Tax treatment of zero-coupon bonds varies by jurisdiction. In the United States, even though no interest is actually received, the annual 'phantom interest' (Original Issue Discount, or OID) is subject to tax each year. In Japan, the redemption gain on a foreign zero-coupon bond may be classified as miscellaneous income subject to aggregate taxation, which can differ from the separate 20.315% tax rate applied to interest income on coupon bonds. Practical guides on discount bond taxation and management are available on Amazon
A common misconception is that zero-coupon bonds are a bad deal because they pay no interest. In reality, because they are purchased at a discount, the effective yield can match or even exceed that of coupon bonds. Moreover, in a falling-rate environment, zero-coupon bonds appreciate faster than coupon bonds, making them attractive for investors who anticipate rate declines. The flip side is that they suffer larger price drops when rates rise.