409A Valuation Audit Defense

A 409A audit defense involves the appraiser responding to auditor challenges on valuation methodology, comparable company selection, DLOM assumptions, and OPM parameters. Choosing an appraiser who provides active audit support — not just a report — is critical for companies with Big 4 auditors.

Published April 20, 2026

3 min read

Key Takeaways

Big 4 auditors test your 409A as part of their stock-based compensation audit procedures

Auditors focus on comparable company selection, growth assumptions, DLOM, and OPM parameters

Your appraiser should actively respond to auditor management letters and comment letters

A well-documented 409A reduces audit time and protects against restatement risk

Restatement of prior-period SBC expense due to a failed 409A is extremely costly

Appraiser selection matters: choose one with experience defending to your specific audit firm

How Big 4 Auditors Review 409A Valuations

When your company undergoes a financial statement audit, your external auditors are required under PCAOB and GAAP standards to test the fair value of stock options granted during the period. This involves a detailed review of your 409A valuation report and, often, direct communication with your appraiser.

The Audit Review Process

A typical Big 4 audit review of your 409A proceeds as follows:

Initial documentation request: Auditors request your 409A report, all supporting schedules, cap table as of the valuation date, and the appraiser's credentials
Reasonableness testing: Auditors perform their own estimate of FMV using the same general approach (often a simplified model) to assess whether your 409A conclusion is within a reasonable range
Comparable company challenge: Auditors often challenge the selection of comparable public companies, asking why specific companies were included or excluded
OPM/PWERM assumption review: Auditors test key assumptions — expected term, volatility, DLOM — against market data and industry benchmarks
Management letter / AJE: If auditors conclude the 409A FMV is materially different from their estimate, they may propose an audit adjustment (AJE) to restate option grant fair values

Common Audit Challenges and Responses

"Your comparable companies are too high-growth": Auditors may argue that selecting high-multiple SaaS comps inflates the enterprise value. Response: Document the selection criteria and why excluded companies are less comparable.
"Your DLOM is too high": If auditors believe the company is closer to a liquidity event than DLOM implies, they will push for a lower discount. Response: Provide board minutes, investor communications, and timeline analysis supporting the assumed liquidity horizon.
"Your revenue projections are too optimistic": DCF-heavy valuations are sensitive to growth assumptions. Response: Tie projections to historical actuals and provide conservative case scenarios.

Choosing an Audit-Ready Appraiser

Not all 409A providers are equal when it comes to audit support. When evaluating providers, ask:

Have they previously defended valuations to your specific audit firm?
Do they provide unlimited audit support, or charge per hour?
What is their track record — have any of their valuations required material restatement?
Are the lead analysts CVAs or ABVs with verifiable credentials?