WACC, Unlevered Returns, and the Tax-Shield Assumption
Summary
The discussion examines why a WACC calculation with debt tax benefits may differ from an unlevered required return derived using CAPM and an adjusted asset beta. One answer attributes the mismatch to combining frameworks with different assumptions: the stated CAPM treatment omits taxes, while conventional WACC applies a tax adjustment to debt costs. It also notes that with no debt, the debt tax adjustment has no effect.
A second answer challenges using WACC as a universal investment hurdle or as a measure that falls simply when leverage rises. It argues that in a perfect market, changing the financing mix does not by itself change total firm value, and that equity returns adjust as leverage changes. These claims are conceptual arguments rather than a settled derivation resolving every modeling convention. The exchange also disputes interpreting beta as the cause of expected returns. Readers should treat the competing claims as a prompt to check assumptions and definitions before comparing discount rates.
Key ideas
- The tax adjustment in conventional WACC applies to debt financing.
- The answers identify a mismatch between tax-adjusted WACC and CAPM treatments that omit taxes.
- The exchange disputes using WACC mechanically as an investment hurdle rate.
- In the perfect-market argument, changing leverage alone does not change total firm value.
- The discussion contains competing views and does not provide a complete reconciliation of all valuation conventions.
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Full text
# Why is there inconsistency in WACC vs unlevered return?
# Why is there inconsistency in WACC vs unlevered return?
To evaluate an enterprise we can discount free cash flow by either the unlevered required rate of return or the WACC.
With Tax we have:
$WACC=R_e \frac{E}{E+D}+R_f\frac{D}{E+D}(1-t)$
where $R_e$ is return on equity, $R_f$ is return on debt or risk free rate, $E$ is market value of equity, $D$ is market value of debt and $t$ is tax.
If the equity beta of the firm is $\beta_e$ we have the unlevered beta or asset beta as: $\beta_A=\beta_e/(1+\frac{D}{E+D}(1-t))$. Also by CAPM:
$R_e=Rf+\beta_e(R_m-R_f)$
$R_A=Rf+\beta_A(R_m-R_f)$
by plugging in the expression for $\beta_A$ and simplifying I get:
$R_A=R_e\frac{E}{E+D(1-t)}+R_f\frac{D(1-t)}{E+D(1-t)}$
This is different from the WACC expression while I think it should be the same. What am I doing wrong?
## Answer by skoestlmeier (score 1)
https://quant.stackexchange.com/a/44018
There may be two points you are missing:
- You are allowed to apply the CAPM to calculate the cost of equity $R_e$. However, one of the CAPM assumptions is, that taxes are not taken into account into the model.
- The unlevered WACC gives a theoretical solution under the assumption that there is no debt at all. In conventional WACC, the tax part $t$ only impacts the cost of debt, but if the weight of debt is zero, tax is not relevant any more.
In summary, the difference from your formulas arises, because the WACC-approach explicitly includes the tax-shield $t$ and the CAPM is an economic model without taxes.
Furthermore, i would like you to point to this wonderful answer, as it may be useful for further details on WACC.
## Answer by Chen Deng-Ta (score 1)
https://quant.stackexchange.com/a/53703
In fact, the WACC is misinforming us; it is neither a cost nor a required return but a weighted average of a cost and a required return. The corporate finance community promotes the WACC as a comprehensive cost of capital to guide investment decisions. This practice is wrong. Suppose that the risk-free rate is 5% (simple rate), and the required rate of return is 10%. If the current D/S=1/4, then the WACC is 9%. Given a project with a constant rate of return at 6%, it is far below the WACC, but the project is profitable because it is an arbitrage opportunity to finance the project by borrowing money. We see that we cannot take the WACC as a hurdle rate
Using the WACC to guide investment decisions, and minimizing the WACC for the optimal capital structure, both are following faulty ideologies. As brainchildren of deterministic and isolated thinking, just as the scientific community finally abandoned the “phlogiston” and “aether” doctrines, we must discard the hypothetical cost of equity capital and renounce the postulated WACC as soon as possible.
A common mistake with WACC is to believe that increasing debt financing can reduce WACC and thus increase the value of a firm. In fact, as long as the total input is invariant, thus future payoff (output) remain the same, the value of a company's securities must remain unchanged in the perfect market. Let WACC be $\rho$, since $\rho=\operatorname{E}(X)/V$, WACC will not be affected by its capital structure. When the debt financing is changed, the cost of equity can not be fixed. As an example, if $\mu>r$ and we replace all the debt $D$ by equity, then the value of stock is increased by $D$, but its payoff is increased by $rD$. Since $$ \mu_{\mathrm{new}}-\mu=\frac{\operatorname{E}(X)}{V}-\frac {\operatorname{E}(X-rD)}{V-D}=-\frac{D}{V}(\mu-r)<0 $$ the cost of equity is decreased.
For more, see The Circular Justification in the MM Proposition: A Rethink or Perfect Market, Arbitrage, and Value Creation in the MM Proposition
It is extremely wrong to use beta to estimate the so-called cost of capital: In CAPM (security market line), the returns are endogenous. It is the result of the equilibrium of the entire market according to the mean-variance criterion, and is not determined by the so-called risk (variance, beta, or covariance). The beta value is calculated from the equilibrium return, using beta value to explain the expected return is a circular argument.
For more on CAPM, see An Analytic Solution to the Mean-Variance Equilibrium: Is the Market Beta a Valuable Tool?Shown in full with attribution under the source's licence. Licence: CC BY-SA 4.0 (Stack Exchange)
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.