DCF Interview Questions: The Complete Walk-Through Guide

Walk me through a DCF is the single most predictable technical question in investment banking interviews, and that predictability is a trap: because everyone prepares a script, interviewers differentiate candidates on the follow-ups. Why unlevered free cash flow? Where does WACC come from? What happens to value if the terminal growth rate rises? Whether your discount rate is even consistent with your cash flows.

A DCF is conceptually simple: a company is worth the present value of the cash it will generate. Everything else is machinery around that idea. If you understand each piece of the machinery well enough to defend it, the follow-ups become easy. This guide takes you through the walk-through, the inputs, the sensitivities, and the mistakes, with real bank questions appended below for practice.

What Interviewers Actually Test

The walk-through itself is a pass/fail filter: a clean two-minute answer keeps you alive but earns no points. Points are earned on depth. Interviewers pick one component, the free cash flow build, WACC, beta, or terminal value, and drill down until they find the edge of your understanding.

They are also testing consistency, the theme that runs through all DCF questions. Unlevered cash flows must be discounted at WACC; levered cash flows at the cost of equity. Nominal cash flows need nominal discount rates. A terminal growth rate must be sustainable forever. Most trick questions are consistency violations in disguise.

Finally, they test intuition about sensitivity: which assumptions actually move the answer. Candidates who know that the output lives and dies on the discount rate and terminal value assumptions, and who can reason about direction without a calculator, stand out immediately.

The Walk-Through You Must Have Cold

Deliver this as a confident, ordered sequence in roughly 90 seconds to two minutes. Practice it out loud, not in your head.

1. 01Project unlevered free cash flows for an explicit forecast period, commonly 5 to 10 years, based on revenue growth, margin, capex, and working capital assumptions.
2. 02Unlevered FCF = EBIT x (1 - tax rate) + depreciation and amortization - capital expenditures - increase in net working capital.
3. 03Calculate the discount rate: WACC, the weighted average cost of capital across debt and equity.
4. 04Estimate terminal value at the end of the forecast period, using either the Gordon growth (perpetuity growth) method or an exit multiple.
5. 05Discount the explicit-period cash flows and the terminal value back to today at WACC to get enterprise value.
6. 06Bridge from enterprise value to equity value: subtract net debt, preferred stock, and minority interest (add back cash if you used gross debt).
7. 07Divide equity value by diluted shares outstanding to get the implied value per share, and sensitize the output across WACC and terminal assumptions.

Unlevered FCF and WACC: The Inputs

Why unlevered free cash flow? Because it is the cash flow available to all capital providers, before interest, which matches a discount rate that blends all capital providers, WACC. Discounting unlevered cash flows at WACC yields enterprise value. The alternative, a levered DCF, discounts free cash flows after interest at the cost of equity and yields equity value directly; it is less common in practice but you should know it exists and why the pairing differs.

WACC = (E/V) x cost of equity + (D/V) x cost of debt x (1 - tax rate), with weights at market values and V = E + D (extend with a preferred term if applicable). The (1 - tax rate) reflects the tax deductibility of interest. Cost of debt is approximated by the yield on the company's debt. Cost of equity comes from the capital asset pricing model: risk-free rate plus beta times the equity risk premium, where beta measures the stock's sensitivity to the market.

For beta, know the unlever/relever logic: take levered betas from comparable companies, unlever each to strip out capital structure, average them, then relever at the target's capital structure. The commonly used formula is unlevered beta = levered beta / (1 + (1 - tax rate) x debt/equity), with the relevering step run in reverse. Note in the interview that this is the standard convention; variants exist. The intuition is what matters: more leverage means more risk to equity holders, hence a higher levered beta and cost of equity.

Terminal Value: Where Most of the Value Lives

Terminal value usually represents well over half of the total DCF value, which is exactly why interviewers probe it. Under the Gordon growth method, terminal value = final year FCF x (1 + g) / (WACC - g), where g is the perpetuity growth rate. The formula explodes as g approaches WACC and is meaningless if g exceeds WACC, a classic trick question: no company can forever grow faster than its discount rate implies, and g should not exceed the long-run growth of the economy, so a rate at or below long-run GDP or inflation growth, often in the low single digits, is standard.

The exit multiple method instead applies a multiple, commonly EV/EBITDA drawn from comps, to the terminal year metric. Best practice is to compute both and cross-check: what growth rate does your exit multiple imply, and what multiple does your growth rate imply? If the implied values are unreasonable, your terminal value is doing something your assumptions cannot defend.

Also worth knowing: the mid-year convention discounts cash flows as if they arrive mid-period rather than at year-end, reflecting that cash comes in throughout the year, which modestly increases present value.

The Classic Questions and How to Think About Them

Directional sensitivity questions are the most common follow-up: what happens to value if WACC increases? Value falls, and the longer-dated the cash flows, the harder they are hit, which is why high-growth companies are more rate-sensitive. If the terminal growth rate rises, value rises, and often dramatically, because of the WACC minus g denominator. If the tax rate rises, unlevered FCF falls, pushing value down, though the after-tax cost of debt also falls slightly; the cash flow effect dominates. Answer these by naming the affected input, the direction, and the intuition in one breath.

Consistency questions are the second family: why do you subtract cash in the bridge (it is non-operating and its interest income is not in unlevered FCF), why can you not discount unlevered FCF at the cost of equity (mismatched investor groups), when would you use a levered DCF, and how would you value a company in a different currency or a bank (banks get a dividend discount model or residual income approach because interest is operational). The framework is always to check that cash flows and discount rate describe the same claim.

Finally, expect the meta question: what are the weaknesses of a DCF? Sensitivity to assumptions, the dominance of terminal value, garbage-in-garbage-out projections, and difficulty with unpredictable cash flows. The strongest answers name a weakness and the practical mitigation, such as sensitivity tables and cross-checking against comps. The bank-tagged questions below this guide cover all three families; drill them out loud.

Common Mistakes

Most DCF stumbles fall into a handful of categories, and interviewers see them daily.

• Subtracting interest expense in an unlevered FCF build, then discounting at WACC anyway, a double count of financing costs.
• Forgetting to discount the terminal value back to today, or discounting it over the wrong number of periods.
• Choosing a terminal growth rate above WACC or above plausible long-run economic growth.
• Reciting the WACC formula but being unable to explain where beta or the equity risk premium comes from.
• Forgetting the EV-to-equity bridge at the end, or dividing by basic instead of diluted shares.
• Presenting the output as one precise number rather than a sensitivity-tested range.

How to Prepare

The walk-through needs to be rehearsed verbally until it is boring, and the component knowledge needs active recall, because follow-ups are unpredictable in order but predictable in content.

WACC Buddy's DCF deck is built around exactly those follow-ups, real questions asked at the banks, resurfaced by spaced repetition until the weak spots are gone.

1. 01Memorize the walk-through as a 7-step sequence and rehearse it aloud until it takes under two minutes.
2. 02Learn the unlevered FCF formula, WACC, and CAPM well enough to explain each term's purpose, not just recite it.
3. 03Drill terminal value both ways and practice the cross-check logic between growth rates and exit multiples.
4. 04Run directional drills: pick an input, move it up or down, and state the effect on value with the intuition.
5. 05In the final week, have someone interrupt your walk-through with random follow-ups, since that is how it happens in the room.

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