The formula PV = C/r assumes that the first cash payment arrives one period from now, not immediately. This timing convention determines how the payment stream is discounted and prevents the present value from overstating or understating the asset’s worth. If the payment timing changes, the valuation procedure must account for that difference.
The discount rate has an inverse relationship with present value. Holding the periodic payment constant, a higher rate produces a lower value because future payments are discounted more heavily. A lower rate produces a higher value. This sensitivity makes the assumed constant rate a central condition in interpreting results from the model.
The constant payment assumption allows the entire indefinite cash-flow stream to be summarized as C/r. Because each period provides the same amount, the model does not require separate valuation of individual payments. If distributions change over time, the simple formula no longer describes the stream directly, creating a need to consider a growing perpetuity or another valuation approach.
A Simple Perpetuity holds the periodic payment constant, whereas a growing perpetuity is designed for payments that increase over time. This distinction matters because the payment pattern determines which valuation framework is appropriate. The simple model therefore provides a baseline for understanding how introducing growth changes the analysis of long-term income streams.
First, identify the constant periodic payment, C, and express the discount rate, r, for the same period. Next, confirm that the first payment occurs one period from now and that the rate remains constant. Finally, divide C by r. The resulting present value summarizes the value of the indefinite payment stream under those assumptions.
The approach supports valuation of preferred stock, perpetual bonds, and other assets that provide fixed ongoing distributions. It helps analysts translate a stable long-term income stream into a present value for investment pricing. The model also serves as a foundation for discounted cash flow analysis and for examining more advanced perpetual-payment structures.