Weighted Average Cost of Capital (WACC)

Weighted average cost of capital (WACC) is the blended rate of return a company must earn on its existing assets to satisfy both its debt holders and equity investors, calculated as WACC = (E/V × Re) + (D/V × Rd × (1 − Tc)), where E is market value of equity, D is market value of debt, V is total capital (E + D), Re is cost of equity, Rd is cost of debt, and Tc is the corporate tax rate. WACC serves as the discount rate for evaluating capital allocation decisions, investment opportunities, and the NPV of operational improvements — including AP and AR automation initiatives. For mid-market companies, WACC typically ranges from 8–15%, meaning every dollar of working capital trapped in slow-paying receivables or missed early-pay discounts has an opportunity cost of 8–15 cents annually. This makes WACC the critical bridge between operational finance metrics (DSO, DPO, discount capture rates) and enterprise value creation. When evaluating AP automation ROI, the cost of capital applied to retained early-pay discounts and reduced float amplifies the value proposition: a $200,000 annual discount capture improvement has a present value of $1.33–$2.5 million at a 8–15% WACC over a 10-year horizon. Similarly, AR automation that reduces DSO by 15 days for a $50 million company unlocks $2.05 million in working capital that, when redeployed at the company's WACC, generates $164,000–$308,000 in annual value. Understanding WACC transforms AP/AR automation decisions from operational expense conversations into strategic capital allocation discussions at the CFO level.