Techniques for Measuring Specific Costs of Capital

Every rupee a company raises to fund its operations comes with a price tag. Borrow money, and lenders want interest. Issue preference shares, and investors expect a fixed dividend. Sell equity shares, and shareholders demand a return that compensates them for the risk they’re taking. This price tag, source by source, is what we call the specific cost of capital. Before you can calculate a company’s overall cost of capital, you first need to work out what each individual source costs. That’s exactly what this topic covers, and once you get comfortable with the formulas, the logic behind weighted average cost of capital (WACC) calculations becomes far easier to follow.

Why specific costs matter before you calculate WACC 🔗

A company rarely relies on a single source of funds. A typical Indian firm might have a mix of debentures, preference shares, equity shares, and retained earnings on its balance sheet. Each of these has a different cost, driven by the return that particular class of investor expects. The specific cost of capital tells you the rate a company must earn on funds raised from that particular source just to keep the provider of that capital satisfied. Once all the specific costs are known, they get combined using their proportion in the capital structure to arrive at the overall or weighted average cost of capital, which then becomes the benchmark for evaluating new projects.

Measuring the cost of debt 🔗

Debt is usually the cheapest source of long-term finance, mainly because interest paid on borrowings is tax-deductible in India. This tax shield lowers the effective cost, which is why every debt-cost formula factors in the tax rate.

Cost of irredeemable or perpetual debt 🔗

When debt does not have a fixed maturity date, the cost is calculated using a straightforward formula that links the after-tax interest outflow to the net proceeds raised from issuing the debt:

Kd = I (1 – t) / NP

Here, I is the annual interest amount, t is the tax rate, and NP is the net proceeds from the issue, meaning the face value minus any discount or floatation cost. Say a company issues a debenture with a face value of ₹100 at a 10% coupon, incurs 2% floatation cost, and falls in the 30% tax bracket. The after-tax interest is ₹10 × (1 – 0.30) = ₹7, and net proceeds are ₹98. The cost of debt works out to 7/98, or roughly 7.14%.

Cost of redeemable debt: the yield to maturity approach 🔗

Most debentures in practice do have a maturity date, and this is where the yield to maturity (YTM) approach comes in. YTM is the discount rate at which the present value of all future interest payments and the redemption value equals the current market price or net proceeds of the debt. In simple terms, it’s the return an investor would earn by holding the bond until it matures, and for the issuing company, it becomes the pre-tax cost of that debt.

Since exact YTM calculations involve trial-and-error or interpolation between two discount rates, students typically use an approximation formula for exam purposes:

Kd (before tax) = [I + (RV – NP)/n] / [(RV + NP)/2]

Where RV is the redemption value, NP is net proceeds, and n is the number of years to maturity. Once this pre-tax figure is found, it’s multiplied by (1 – t) to arrive at the after-tax cost, since interest remains tax-deductible regardless of whether the debt is redeemable. This method is widely used because it accounts for the fact that money received or paid at different points in time carries different present values, which the YTM approach captures more accurately than a simple flat calculation.

Measuring the cost of preference capital 🔗

Preference shares sit between debt and equity. Dividends on them are fixed, similar to interest on debt, but unlike interest, preference dividends are not tax-deductible, since they’re paid out of profit after tax. This makes preference capital costlier than debt for the company, even though the dividend rate might look similar to a debenture’s coupon rate.

Irredeemable preference shares 🔗

For preference shares with no maturity, the cost is simply the annual preference dividend divided by the net proceeds from the issue:

Kp = PD / NP

If a company issues ₹100 preference shares with a 9% dividend rate and incurs 3% issue expenses, net proceeds are ₹97, and the cost works out to 9/97, or about 9.28%. Notice this is higher than the after-tax cost of debt calculated earlier, which illustrates why preference capital typically costs more than debt but less than equity.

Redeemable preference shares 🔗

Just like redeemable debt, redeemable preference shares use an approximation formula that spreads any capital gain or loss on redemption over the life of the shares:

Kp = [PD + (RV – NP)/n] / [(RV + NP)/2]

The logic mirrors the debt formula exactly, minus the tax adjustment, since preference dividends don’t reduce the company’s tax liability.

Measuring the cost of equity capital 🔗

Equity is the trickiest source to price because equity shareholders have no contractual right to a fixed return. Their expected return is implicit, shaped by dividends they anticipate and the growth they expect in the company’s earnings. Two approaches dominate this measurement: the dividend discount model and the capital asset pricing model.

The dividend discount model (Gordon growth model) 🔗

This model assumes a company’s share price today reflects the present value of all future dividends, growing at a constant rate forever. Rearranging that relationship gives the formula used to estimate the cost of equity:

Ke = D1 / P0 + g

Where D1 is the dividend expected next year, P0 is the current market price of the share, and g is the constant expected growth rate in dividends. This is often called the dividend growth model, and it essentially says the cost of equity equals the dividend yield plus the expected growth rate. If a company’s current market price is ₹200, next year’s expected dividend is ₹10, and dividends are expected to grow at 5% annually, the cost of equity comes to (10/200) + 0.05, which equals 10%.

The model works well for stable, dividend-paying companies, but it has a real limitation: it assumes dividends grow at a constant rate indefinitely, which rarely holds true for younger or high-growth firms that reinvest most of their earnings instead of paying them out.

CAPM as an alternative 🔗

For companies where dividend patterns are erratic or where the market provides better data on risk, the Capital Asset Pricing Model offers an alternative:

Ke = Rf + β (Rm – Rf)

Here, Rf is the risk-free rate, often proxied using yields on Indian government securities, β measures the stock’s volatility relative to the market, and Rm is the expected market return. CAPM links the cost of equity directly to systematic risk rather than dividend behaviour, which is why it’s often used alongside, or instead of, the dividend discount model.

Cost of retained earnings 🔗

Retained earnings might feel like “free money” since the company doesn’t have to issue new shares or pay any transaction costs to access them. But that’s a misconception. Retained earnings belong to equity shareholders, and by keeping them within the business instead of paying them out as dividends, the company is implicitly asking shareholders to accept the same return they’d expect from equity capital. So the cost of retained earnings is generally treated as equal to the cost of equity, sometimes adjusted slightly downward to account for the personal taxes shareholders would have paid had the earnings been distributed as dividends, or the brokerage costs they’d incur reinvesting that dividend elsewhere.

Putting the specific costs together 🔗

Here’s a quick comparison of how these sources typically stack up in terms of cost, from cheapest to most expensive:

This ranking explains a lot about corporate financing behaviour. Companies generally prefer debt first because it’s cheaper and interest payments reduce taxable income. Equity is used more cautiously because it’s the costliest source and dilutes ownership. Once every specific cost is measured this way, a company can plug the figures into the WACC formula, using each source’s proportion in the capital structure as weights, to determine the overall hurdle rate for evaluating new investments.

What do you think? If a company has both a strong credit rating and a volatile stock price, would you expect the gap between its cost of debt and cost of equity to widen or narrow, and why? And when a firm’s dividend history is too irregular to apply the dividend discount model reliably, which alternative approach would you trust more for estimating its cost of equity?

References

1. https://www.accountingtools.com/articles/cost-of-capital-formula
2. https://corporatefinanceinstitute.com/resources/valuation/cost-of-debt/
3. https://analystprep.com/cfa-level-1-exam/corporate-finance/cost-debt-capital/
4. https://www.accaglobal.com/us/en/student/exam-support-resources/fundamentals-exams-study-resources/f9/technical-articles/capm-1.html