Irredeemable debt

For a simple fixed-interest irredeemable security, value is annual interest divided by the investor's required return. The corresponding current yield is interest divided by the ex-interest market price. For the issuer's simple after-tax cost, use interest net of usable tax relief in the numerator. These perpetuity calculations assume payments continue and a constant appropriate rate; credit risk and embedded options can complicate valuation. A perpetual instrument is not necessarily ordinary equity, and a quoted coupon percentage is based on nominal value rather than its current market price.