Mergers and acquisitions are among the most scrutinized financial events a company can undergo. The due diligence process is designed to surface material risks before a transaction closes — but one area that consistently receives less attention than it deserves is how a company’s assets, equity, and liabilities have been valued, and whether those valuations meet the regulatory and professional standards that acquirers, auditors, and courts will later examine.
When valuation work is done incorrectly during due diligence — whether through outdated assumptions, missing documentation, or the wrong methodology — the consequences rarely surface immediately. They tend to emerge months later, during audits, post-close purchase price adjustments, or regulatory reviews. By that point, the deal is done, and the cost of correcting the record falls entirely on the acquiring entity.
What follows is a structured account of the most common and consequential mistakes US companies make in this area — not as a checklist of abstract warnings, but as a practical account of what goes wrong, why it goes wrong, and what the downstream impact looks like.
1. Treating Valuation as a One-Time Event Rather Than a Governed Process
Many companies approach business valuation as something that happens once — when a transaction is being structured — rather than as an ongoing, governed discipline. This misunderstanding is at the root of most due diligence failures. Proper valuation compliance requires that valuations be defensible not just at the time they were prepared, but at any future point when they may be reviewed by an auditor, a regulator, or a counterparty’s legal team.
Why Point-in-Time Thinking Creates Long-Term Exposure
When a valuation is treated as a one-time deliverable rather than part of a documented process, there is often no clear record of the assumptions used, the comparable data referenced, or the rationale for choosing one methodology over another. If any of those choices are later questioned — which they frequently are during purchase price allocation reviews or goodwill impairment testing — the company has no paper trail to support its position. This creates both financial and legal exposure that a properly governed valuation process would have avoided entirely.
2. Misapplying the Income, Market, and Asset Approaches
There are three broadly accepted approaches to business valuation: the income approach, the market approach, and the asset approach. Each is appropriate for different types of businesses and transaction contexts. A profitable operating company with predictable cash flows is typically valued using the income approach. A company being liquidated or an asset-heavy business may be better suited to the asset approach. The market approach relies on comparable transactions or public company multiples and works best when there are genuinely comparable data points available.
The Risk of Defaulting to Familiarity
The problem during due diligence is that companies — and even some valuation analysts — default to the method they are most comfortable with rather than the one most appropriate to the situation. Applying a market-based multiple to a company in a niche industrial sector where no true comparables exist, for example, can produce a value that looks defensible on the surface but is difficult to justify under examination. Auditors and the IRS are both well-positioned to challenge methodology choices that are not grounded in the specific facts of the business being valued.
3. Failing to Separate Personal and Enterprise Goodwill
In acquisitions involving founder-led or owner-operated businesses, one of the most consequential valuation errors is the failure to distinguish between enterprise goodwill and personal goodwill. Enterprise goodwill is transferable — it belongs to the business and moves with it after an acquisition. Personal goodwill is tied to a specific individual and does not transfer.
Why This Distinction Has Both Financial and Tax Consequences
Failing to make this distinction results in overpayment for goodwill that the acquirer will never actually receive. It also has tax implications: personal goodwill, when properly identified and documented, can receive capital gains treatment for the seller, while enterprise goodwill may be treated differently. Courts have consistently weighed in on this issue, and deal structures that do not account for the distinction create risk on both sides of the transaction. The IRS has guidance on this separation, and acquirers who do not require it during due diligence are leaving themselves exposed.
4. Using Outdated or Internally Generated Financial Projections
Income-based valuations are heavily dependent on the quality of the financial projections used as inputs. During due diligence, many target companies present projections that were prepared internally, without third-party review, and often with optimistic assumptions that have not been stress-tested against market conditions or historical performance.
The Gap Between Projection and Reality
When these projections are accepted at face value and used as the basis for a discounted cash flow analysis, the resulting valuation may be significantly inflated. Post-close, when actual performance diverges from projected performance — as it frequently does — the acquirer is left with an asset that is worth less than what was paid for it, and goodwill that may require impairment. The fix is straightforward: projections used in valuation work should be reconciled against historical performance and subjected to independent review before they are accepted as credible inputs.
5. Overlooking Intangible Asset Identification and Allocation
Under ASC 805, the accounting standard governing business combinations in the United States, acquirers are required to identify and measure all intangible assets acquired in a transaction at fair value as of the acquisition date. This includes customer relationships, trade names, developed technology, non-compete agreements, and other identifiable intangibles that are separate from goodwill.
What Happens When Intangibles Are Bundled Into Goodwill
When companies fail to properly identify and value individual intangible assets, those values get absorbed into the goodwill line — which is not amortizable under current accounting rules. This creates a misstatement in the financial statements, understates amortizable assets, and can trigger restatement requirements if identified during an audit. The Financial Accounting Standards Board has been clear about the requirements under ASC 805, and auditors are actively reviewing purchase price allocations for completeness.
6. Ignoring the Qualified Appraiser Requirement
Certain valuations — particularly those used for tax reporting purposes, charitable contributions of non-cash assets, or estate and gift tax filings — must be performed by a qualified appraiser as defined under IRS regulations. This is not a general best practice; it is a legal requirement. Using an internal finance team or an unqualified analyst for these valuations, regardless of their technical skill, does not satisfy the standard.
The Cost of Non-Compliance with Qualification Standards
When valuations used for tax purposes are later found to have been prepared by someone who does not meet the qualified appraiser definition, the IRS can disallow the reported values, impose penalties, and require the company to defend its positions under heightened scrutiny. This is an avoidable problem — one that stems from a misunderstanding of when qualification standards apply and a failure to build that requirement into the due diligence process from the outset.
7. Neglecting Contingent Consideration Valuation
Earn-outs and other forms of contingent consideration are common in M&A transactions, particularly where there is uncertainty about future performance or a valuation gap between buyer and seller. Under ASC 805, contingent consideration must be measured at fair value on the acquisition date and remeasured at each subsequent reporting period until it is settled.
Why Earn-Out Accounting Is Frequently Mishandled
Many companies treat earn-outs as straightforward contractual obligations rather than as complex financial instruments that require probabilistic modeling and fair value measurement. When the earn-out is not properly valued at closing, and when the remeasurement process is not built into the post-close financial reporting workflow, the company will face audit findings and potentially material misstatements. The valuation of contingent consideration is a technical discipline, and treating it as an administrative item is a consistent source of problems.
8. Not Documenting the Valuation Methodology Contemporaneously
A valuation is only as defensible as its documentation. In practice, many companies allow significant time to pass between when a valuation is performed and when the supporting documentation is actually written up. This creates risk because memory fades, analysts move on, and the reasoning behind specific judgments becomes difficult to reconstruct after the fact.
How Documentation Gaps Create Audit and Litigation Risk
When documentation is incomplete or was clearly prepared after the fact, auditors and opposing counsel treat the valuation with suspicion — regardless of whether the underlying analysis was technically sound. Courts and regulators are specifically attuned to documentation that appears to have been reverse-engineered to support a predetermined number. Contemporaneous documentation — prepared at the time the work is being done — is the standard that withstands scrutiny.
9. Skipping Independent Review of the Target’s Existing Valuations
Targets frequently present existing valuations — for equity awards, goodwill, or prior acquisitions — as part of their data room materials. Acquiring companies sometimes accept these valuations without independent review, particularly when timelines are compressed and there is pressure to move quickly.
The Inherited Risk of Accepting Prior Valuation Work Uncritically
Prior valuations may have been prepared for a different purpose, under different market conditions, or using assumptions that no longer hold. When an acquirer incorporates these valuations into their own financial statements or uses them as a basis for purchase price allocation without independent verification, they inherit whatever errors or omissions the original work contained. An independent review — even a limited one — provides a critical filter that protects the acquiring company from taking on valuation risk it did not knowingly accept.
10. Underestimating the Role of Valuation in Post-Close Integration
Due diligence ends at closing, but the financial reporting consequences of valuation decisions extend well beyond it. The fair values assigned to acquired assets and liabilities at closing determine depreciation and amortization schedules, affect future impairment testing, and shape the earnings profile of the combined entity for years after the transaction is complete.
How Closing-Date Decisions Create Long-Tail Reporting Consequences
Companies that treat valuation compliance as a due diligence box to check — rather than as a set of decisions with multi-year financial reporting implications — often find themselves revisiting those decisions under pressure. When goodwill impairment tests reveal that an acquisition was overpriced, or when amortization schedules do not align with the actual useful lives of acquired assets, the root cause can often be traced back to valuation work that was insufficiently rigorous at the time of closing.
Closing Thoughts
The pattern across these ten mistakes is consistent: valuation errors in M&A due diligence are rarely the result of technical ignorance. They are more often the result of compressed timelines, misplaced confidence in informal processes, and a failure to apply the same rigor to valuation work that companies routinely apply to legal, financial, and operational due diligence.
The stakes are high enough that this gap deserves direct attention. A transaction that is structurally sound but built on a weak valuation foundation carries hidden risk that can take years to fully surface — and by then, it becomes far more expensive to address than it would have been to prevent.
Companies that invest in defensible, well-documented, methodologically appropriate valuation work during due diligence are not being overly cautious. They are protecting the financial integrity of the transaction from the inside out — which is exactly what the due diligence process is designed to accomplish.
