How Tariffs Are Rewriting the M&A Due Diligence Playbook

Two years ago, tariff exposure was a line item buried in the appendix of most due diligence reports. Today, it occupies a central position in how buyers evaluate acquisition targets, structure purchase agreements, and model financial projections. The shift has been rapid, and it is reshaping deal mechanics across the middle market.

The U.S. tariff landscape in 2025 and 2026 has introduced a level of trade policy volatility that most dealmakers have not encountered in their careers. Shifting rates on Chinese imports, new duties on specific industrial categories, and retaliatory measures from trading partners have created a moving target for companies with any meaningful cross-border supply chain exposure. For buyers conducting due diligence on potential acquisitions, this uncertainty has fundamentally changed what they need to understand before committing capital.

Supply Chain Diligence Is Now Mandatory

The most visible change is the elevation of supply chain analysis from a secondary diligence workstream to a primary one. Buyers are now mapping the full tariff exposure of a target company's supply chain before they reach a term sheet, not after.

This means tracing raw materials, components, and finished goods back to their country of origin. It means understanding which tariff classifications (HTS codes) apply to each major input. It means modeling the financial impact of current tariff rates, potential rate increases, and the cost of shifting to alternative suppliers. For companies in manufacturing, consumer products, and industrial distribution, this analysis can materially change the valuation.

A buyer who fails to account for this in diligence is overpaying.

Financial Model Stress Testing

Beyond supply chain mapping, tariff risk is changing how buyers stress-test financial projections. The traditional approach to building a deal model (projecting revenue growth, applying margin assumptions, and discounting back to present value) assumed a relatively stable cost structure. That assumption no longer holds for businesses with significant import exposure.

Sophisticated buyers are now running multiple tariff scenarios through their models. A base case that assumes current tariff rates continue. A downside case that models the impact of proposed or threatened rate increases. An upside case that assumes some tariff relief or trade agreement normalization. The spread between these scenarios can be substantial, and it directly affects what a buyer is willing to pay.

This also affects how earn-out structures are designed. If a seller's earn-out is tied to EBITDA performance, and tariff changes could materially depress margins through no fault of the seller's management team, both parties need to agree on how tariff-driven cost increases are treated in the earn-out calculation. Buyers and sellers are increasingly negotiating tariff-specific adjustments into these provisions.

Contract and Legal Diligence Has Expanded

Tariff risk has also expanded the scope of legal and contractual diligence. Buyers are scrutinizing several areas with new intensity.

Material adverse effect (MAE) clauses are being renegotiated to address whether a significant tariff change constitutes a MAE that would allow a buyer to walk away from a signed deal. The answer depends on how the clause is drafted, and both sides are paying closer attention to the language.

Supplier contracts are being reviewed for price adjustment mechanisms. Does the target company have long-term supply agreements with fixed pricing, or do its contracts allow suppliers to pass through tariff-related cost increases? The answer significantly affects the target's cost predictability and, by extension, its valuation.

Customer contracts receive similar scrutiny. Can the target company raise prices to offset higher input costs, or are its customer agreements structured in a way that limits pricing flexibility? Companies with strong pricing power and contractual escalation provisions are commanding premiums in the current market.

The Domestic Acquisition Shift

One strategic response to tariff uncertainty has been a shift toward domestic acquisitions. Companies that might previously have looked to acquire overseas suppliers or manufacturing capacity are instead consolidating domestically. The logic is straightforward: a domestic acquisition eliminates cross-border tariff exposure for the acquired business's operations, simplifies the supply chain, and reduces regulatory complexity.

This trend is particularly visible in the middle market, where companies in industrial distribution, food and beverage, and specialty manufacturing are acquiring domestic competitors to build scale and reduce dependence on imported inputs. For business owners in these sectors, the tariff environment has created a window of heightened buyer interest.