409A Valuation Guide for CPAs: Safe Harbors, the 12-Month Rule and What Auditors Check

A 409A valuation is an estimate of the fair market value of a private company's common stock, used to set the exercise price of stock options so the options stay outside Internal Revenue Code section 409A. If the strike price is below fair market value on the grant date, the option is generally treated as deferred compensation that fails 409A's rules, and the employee faces tax consequences that the company is also expected to report and withhold on.

CPAs run into 409A from three sides: clients ask the firm for a valuation, auditors test the stock compensation expense that rests on it, and tax preparers deal with reporting when it goes wrong. This guide covers the rule, the safe-harbor methods, the penalty, the link to ASC 718, and the audit procedures.

Why the exercise price matters

Under Treasury Regulation 1.409A-1(b)(5)(i)(A), a stock option on service recipient stock is not deferred compensation only if all of these hold:

• the exercise price can never be less than the fair market value of the underlying stock on the grant date, and the number of shares is fixed on the grant date;
• the transfer or exercise of the option is taxed under section 83; and
• the option has no feature that defers compensation beyond the later of exercise or disposition (or, for the stock, when it becomes substantially vested).

Pricing at fair market value is necessary but not enough alone. An option that fails is deferred compensation, and then 409A's rules on timing of payment and elections apply.

The valuation standard and the three presumed methods

For stock not readily tradable on an established securities market, Treasury Regulation 1.409A-1(b)(5)(iv)(B)(1) requires a value set by reasonably applying a reasonable valuation method, judged on facts at the valuation date. Relevant factors include asset values, projected cash flows, market values of comparable businesses, arm's-length transactions, and adjustments such as control premiums or marketability discounts. A method is unreasonable if it ignores information that is available and material to the company's value.

Paragraph (B)(2) presumes a valuation reasonable if made by one of three methods. The IRS can rebut the presumption only by showing the method or its application was grossly unreasonable.

The independent appraisal is the method most private companies use. The start-up method has narrow conditions, and the appraiser must be qualified, generally meaning at least five years of relevant experience.

The 12-month rule and material events

A previously calculated value is unreasonable for a later date if it ignores later information that may materially affect value, or if it was calculated more than 12 months before the date it is used. Both limbs matter. A 7-month-old appraisal can fail if the company closed a priced round, received an acquisition offer, lost its largest customer or changed its forecasts materially since the valuation date. The practical response is a rule in the equity plan administration process: before each grant batch, someone documents whether anything material has occurred since the last valuation, and the answer goes in the file.

The penalty for a failed option

Section 409A(a)(1)(B) sets the consequences when a plan fails the requirements. The employee includes the deferred amounts in income when they are no longer subject to a substantial risk of forfeiture, owes interest at the underpayment rate plus one percentage point computed from when the amount was first deferred or vested, and owes an additional 20 percent tax on the included amount. The company has reporting and withholding obligations, which makes the tax cost a company issue too.

Illustrative example

All numbers are illustrative. A company's most recent independent appraisal, dated March 1, 2026, valued common stock at $2.00 per share. On September 15, 2026 the company closed a preferred round at a price far above that value, and on October 15, 2026 the board granted 100,000 options at a $2.00 exercise price, relying on the March appraisal.

The appraisal is well under 12 months old, but the financing is information that may materially affect value and the grant price ignored it. Suppose a refreshed valuation puts common at $3.50 on the grant date. The discount is $3.50 - $2.00 = $1.50 per share, or $150,000 across 100,000 options. If an employee's included amount in a year were $100,000, the additional tax is 20 percent, or $20,000, before interest and ordinary income tax. The fix is to price at $3.50 before the grant, or to reprice or correct under IRS procedures where the facts allow. The company should not rely on the March figure.

How 409A differs from ASC 718 fair value

The two are different measurements, and mixing them up is the most common review note on stock compensation.

The 409A common stock value is often an input to the option pricing model, so a weak 409A value flows into the ASC 718 expense. For public-company-bound startups, a grant price that looks low relative to a later financing or IPO price is the "cheap stock" question. The AICPA's accounting and valuation guide on equity securities issued as compensation (2013) is the practice reference for valuing private-company equity in this setting. See ASC 718 for private companies and stock-based compensation.

What auditors check

1. Valuation date and age. Agree each grant date to a valuation that is no more than 12 months old, and look for material events between the valuation date and each grant.
2. Who prepared it. An outside valuation firm is a management's specialist. See using the work of a specialist and management's specialist. Evaluate competence, capabilities and objectivity and the appropriateness of the work.
3. Method and inputs. Examine the approach (income, market or asset), the allocation of value to common (for example an option pricing method or a probability-weighted expected return method), discounts, and consistency with board forecasts and financing terms. These are significant estimates under AU-C 540.
4. Reconciliation to transactions. Compare the common value to preferred prices in recent rounds and secondary sales. Ask for the reconciliation.

Independence when the firm does the valuation

For an attest client, appraisal, valuation or actuarial services can impair independence when the results are material to the financial statements and the service involves a significant degree of subjectivity (AICPA Code ET 1.295.150). A 409A valuation for an audit client can meet that description if the resulting stock compensation is material. The firm should assess it before accepting the work. See nonattest services.

Common mistakes

• Relying on a valuation older than 12 months or ignoring a financing, term sheet or acquisition offer since the valuation date.
• Treating the 409A value as the ASC 718 fair value of the option itself.
• Assuming a grant price at fair market value alone makes the option exempt, without considering the other conditions in Reg. 1.409A-1(b)(5)(i)(A).
• Applying the start-up method to a company that does not meet the 10-year and no-put-or-call conditions.
• Failing to document board approval of the exercise price on the grant date.

FAQ

What is a 409A valuation?

It is an estimate of the fair market value of a private company's common stock, used to set option exercise prices so that options are not deferred compensation under section 409A.

How long is a 409A valuation good for?

At most 12 months under the independent appraisal method, and less if a material event occurs that the valuation does not reflect.

What happens if an option is granted below fair market value?

The option generally fails to qualify for the exclusion. The employee includes amounts in income when they vest, pays interest at the underpayment rate plus one percentage point and an additional 20 percent tax.

Is a 409A valuation the same as an ASC 718 valuation?

No. The 409A valuation measures the value of the stock for the exercise price test. ASC 718 measures the grant-date fair value of the award for expense recognition. The first is often an input to the second.

Does a 409A valuation need an independent appraiser?

Using a qualified independent appraisal meeting the regulation's standards gives the presumption of reasonableness. A company can use another reasonable method, but it then bears the burden of showing reasonableness without the presumption.

Sources

• Treasury Regulation 26 CFR 1.409A-1(b)(5)(i)(A) and (b)(5)(iv)(B), Cornell LII and eCFR
• 26 U.S.C. 409A(a)(1)(B), Cornell LII
• AICPA, Accounting and Valuation Guide, Valuation of Privately-Held-Company Equity Securities Issued as Compensation (2013)
• AICPA Code of Professional Conduct, ET 1.295.150, Appraisal, Valuation and Actuarial Services
• FASB ASC 718, Compensation, Stock Compensation

AU-C references are to AICPA Professional Standards, paraphrased here; read the standard itself before relying on a requirement. This page is guidance, not professional advice. Report an error