How do step-up coupon bonds work and why would an issuer choose this structure?

A step-up coupon bond has a coupon rate that increases at scheduled intervals during the bond's life. The increases are predetermined at issuance and specified in the bond indenture.

Example — Northfield Energy Step-Up:

• Par: $1,000
• Maturity: 10 years
• Coupon schedule:
• Years 1-3: 3.5%
• Years 4-6: 4.5%
• Years 7-10: 5.5%

Why Issuers Choose Step-Ups:

1. Lower initial interest expense: A startup or project-finance borrower may have limited cash flow initially but expects growing revenues. Step-ups match the payment schedule to the cash flow trajectory.

1. Incentive to call: Many step-up bonds include a call provision. The rising coupon pressures the issuer to refinance (call the bond) before the coupon gets too expensive. This benefits investors who receive either the higher coupon or a call premium.

1. Credit migration compensation: For lower-rated issuers, step-ups compensate bondholders for the risk of holding the bond longer — if the issuer's credit improves, they call; if not, the investor receives a higher coupon.

1. Regulatory capital: Banks issue step-up bonds as part of Tier 2 capital. The step-up incentivizes the bank to call and replace the bond, ensuring capital instruments are periodically refreshed.

Valuation Approach:

Value each cash flow at the appropriate spot rate:

Price = Sum of [Coupon(t) / (1 + spot_rate(t))^t] + [Par / (1 + spot_rate(n))^n]

For the Northfield example with a flat 4% yield curve:

Duration Consideration:

Step-up bonds have lower duration than equivalent fixed-coupon bonds because the cash flow is more back-loaded in dollar terms, but the coupon increases partially offset the time-value discounting.

CFA Exam Tip: If given a step-up bond, don't use a single coupon rate — model each period's cash flow separately.

Practice step-up bond valuation in our CFA fixed income question bank.