Quick Orientation

Inflation-linked bonds (ILBs) are designed to protect investors against inflation by linking either the principal or coupon payments to an official inflation index. Their main purpose is to preserve the investor’s real purchasing power.

Key Features

Feature Description
Inflation Protection Principal and/or coupon payments rise with inflation.
Real Return Investors earn a real yield (over inflation), not a nominal one.
Indexation Usually linked to CPI, RPI (UK), or other national inflation measures.
Lower Nominal Coupon Base coupons are usually lower than regular bonds because inflation is added later.
Tax Treatment Inflation adjustments may be taxable (varies by jurisdiction).
Long Duration Often issued with long maturities (10–30 years) to hedge long-term inflation risk.

1. Principal-Indexed Bonds (Most Common)

The face value of the bond increases with inflation. The coupon rate is fixed but is applied to the inflation-adjusted principal.

Example: Original principal: $1,000; Annual coupon: 2%; Inflation: 5%.
Adjusted principal = $1,000 × 1.05 = $1,050.
Annual coupon = 2% × $1,050 = $21.

2. Coupon-Indexed Bonds (Less Common)

The coupon payment is directly linked to inflation, but the principal is fixed.

Example: Principal: $1,000; Coupon: CPI inflation + 1%; Inflation: 4%.
Annual coupon = 4% + 1% = 5% → $50 payment. The principal remains $1,000.

🇺🇸 TIPS (Treasury Inflation-Protected Securities) – USA

U.S. government bonds whose principal value adjusts with the U.S. CPI-U. Maturities are 5, 10, and 30 years. If deflation occurs, the principal will not fall below the original par value.

🇬🇧 Index-Linked Gilts – United Kingdom

UK government bonds where both principal and coupons are linked to the Retail Price Index (RPI), with a lag of about 3 months.

🇫🇷 OATi & OAT€i – France

French Treasury issues two types: OATi (linked to French CPI) and OAT€i (linked to Eurozone HICP).

🇮🇹 BTP Italia – Italy

Italian government bonds indexed to the Italian CPI, often sold directly to retail investors.

🇯🇵 JGBi – Japan

Japanese inflation-linked government bonds that link principal to Japan’s CPI. They include a "deflation floor" ensuring investors receive at least 100% of the original principal.

Feature Nominal Bond Inflation-Linked Bond
Coupon Fixed Fixed rate × inflation-adjusted principal
Principal Fixed Adjusts with inflation
Risk Inflation risk to investor Inflation risk transferred to issuer
Yield Nominal yield Real yield
Use Case Income generation Purchasing power protection

Breakeven Inflation Rate (BEI) = Nominal Yield – Real Yield

The BEI is the market’s expectation of average inflation over the bond’s life. If you expect actual inflation to be higher than the BEI, the inflation-linked bond is attractive. If you expect it to be lower, the nominal bond is better.

Example: 10Y Treasury nominal yield = 4.5%; 10Y TIPS real yield = 2.0%.
BEI ≈ 4.5% - 2.0% = 2.5%. If you think inflation will average >2.5%, buy TIPS.

Q: How does a TIPS bond protect against inflation?
A: Its principal is indexed to the CPI. Coupons are paid on the adjusted principal, and you receive the final inflation-adjusted amount at maturity, preserving purchasing power.
Q: What is “breakeven inflation”?
A: It’s the difference between the yield on a nominal bond and an inflation-linked bond of the same maturity. It represents the market's average inflation expectation over that period.
Q: What happens if there’s deflation?
A: The principal and coupons may shrink. However, many ILBs like TIPS have a "deflation floor," meaning the principal paid at maturity will not be less than the original par value.