DCF Assumption Audit Trail

Use This Skill When

• The user wants to review an existing DCF rather than build one from scratch.
• The valuation output looks overly precise, too favorable, stale, or internally inconsistent.
• The task is to pressure-test the operating assumptions, discount rate logic, and terminal value framing.
• A research note, model, or committee memo needs an audit trail explaining which assumptions matter most.

Required Inputs

• The DCF model output or a list of assumptions used.
• Forecast horizon, revenue growth path, margin path, reinvestment assumptions, tax rate, and terminal method.
• WACC inputs or discount rate logic if available.
• Bull, base, and bear cases if the model includes scenarios.
• The user objective: challenge a target price, review someone else's model, or tighten internal valuation discipline.

Workflow

1. Inventory the major operating assumptions: growth, margins, working capital, capex, reinvestment intensity, and terminal economics.
2. Review discount rate construction for stale beta, inconsistent capital structure, unsupported ERP choices, or circular logic.
3. Test internal consistency across the model. Growth, margins, reinvestment, and terminal returns on capital must fit together.
4. Identify where false precision appears, such as narrow scenario ranges, unsupported decimal-level certainty, or terminal assumptions disconnected from industry structure.
5. Determine which assumptions dominate valuation sensitivity and whether the model is effectively a single-variable bet.
6. Summarize the material flaws, needed corrections, and the revised confidence level in the DCF conclusion.

Output Requirements

• Write in a valuation-review tone appropriate for internal model challenge or investment committee prep.
• Organize the output into assumptions, issues, sensitivity concentration, and correction priorities.
• Be explicit about why an assumption is weak: stale, circular, inconsistent, over-precise, or unsupported by economics.
• Use directional correction language when exact recalculation is not possible.
• Keep the analysis assumption-level, not just conclusion-level, so another analyst can revise the model from it.

Output Template

Quality Checks

• Confirm the audit covers both operating assumptions and discount-rate mechanics.
• Check that the terminal value logic is tested against mature-state industry economics.
• Verify the output identifies where assumptions contradict each other, not just where they seem aggressive.
• Make sure sensitivity concentration is called out clearly if one or two variables drive most of the value.
• Ensure scenario analysis is judged for balance rather than treated as valid merely because multiple cases exist.

Guardrails

• Do not accept management guidance as sufficient support for multi-year DCF inputs.
• Do not treat a mathematically clean model as economically sound.
• Do not ignore terminal assumptions; many flawed DCFs hide bias there.
• Do not present unsupported precision in discount rate, perpetuity growth, or exit multiple assumptions.
• Do not overstate certainty if the available model detail is incomplete.

Example Prompts

• Audit this DCF on Adobe and tell me which assumptions are doing most of the work.
• Review whether a 4.5% terminal growth rate and steady margin expansion are internally consistent for a mature software company.
• I have a buy-side model that looks too neat. Build an audit trail of the weakest assumptions and the likely valuation bias.