The debate on US tariffs and M&A has been dominated by sector data and macroeconomic figures. However, little attention has been paid to what happens with international contracts already signed, and with corporate transactions that were underway when the landscape shifted following the measures announced by the Trump administration.
Since July 2025, when the European Union and the United States agreed on a general 15% tariff on European exports — with steel and aluminum subject to 50% under Section 232 — public attention has focused on export figures and available support measures. Spain’s employers’ confederation, CEOE, rejected the agreement for fragmenting markets. The Government mobilized more than €5.5 billion in support instruments. The agri-food, industrial, and pharmaceutical sectors assessed their exposure.
One technical question remains, with very real consequences: what happens legally to contracts signed before the tariff shift? And to M&A transactions that were under negotiation when the disruption hit?
The Contract That No Longer Adds Up
Any Spanish company with supply or service commitments toward US counterparts has run into a problem. So have those with clients embedded in transatlantic value chains. The economic balance of the contract has changed substantially: costs rise, margins disappear or reverse. Yet the contract, signed under market conditions that no longer exist, remains formally enforceable.
This is a classic problem that resurfaces whenever a major external disruption occurs: the rebus sic stantibus clause. In Spain, without specific regulation in the Civil Code but built through case law, it allows a contract to be revised or terminated when an extraordinary change in circumstances makes performance excessively burdensome. However, the Supreme Court has applied it restrictively. It requires the change to be unforeseeable, supervening, and outside the risk sphere assumed by the parties.
Whether the current tariff situation meets those requirements is a case-by-case question. It depends on the date of the contract. It also depends on whether a price-revision clause existed, on the tariff risk contemplated in the agreed allocation, and on the governing law.
When the Contract Is International
In international contracts subject to the Vienna Convention on Contracts for the International Sale of Goods (CISG), the scenario changes. Article 79 governs supervening impediments, but the prevailing case law holds that it does not cover cases of excessive onerousness or hardship — that is, cases where performance remains possible but has become economically unbalanced. A tariff that raises the cost of the contract but does not prevent its performance does not trigger Article 79.
On the other hand, another instrument exists for those cases: the UNIDROIT Principles (Articles 6.2.1 to 6.2.3). They expressly regulate excessive onerousness and provide for a duty to renegotiate. However, they only bind the parties if they have incorporated them into the contract, or if an arbitrator applies them as lex mercatoria. The practical conclusion is the same under both frameworks: everything depends on what the signed contract says.
And that is precisely the problem. Many companies today hold contracts in force that their legal advisors should be reviewing. Moreover, they are not doing so, because the matter is handled as a commercial or logistical issue — not as what it also is: a contractual problem with concrete legal implications.
US Tariffs and M&A: The Impact on Corporate Transactions
The second front is perhaps more relevant for those currently inside an M&A or investment process. This concerns the effect on ongoing corporate transactions.
A company sale or a capital entry takes between six and eighteen months. During that time, the value of the asset can shift considerably. M&A agreements manage that uncertainty through well-known mechanisms: representations and warranties, price adjustments such as locked-box or completion accounts, and Material Adverse Change (MAC) clauses. The latter allow a party to walk away from the deal if the business deteriorates materially between signing and closing.
The debate that has occupied M&A practices in recent months has been this: does the tariff impact justify triggering a MAC clause? As always, it depends on how the clause is drafted. Well-drafted MAC clauses, following standard Anglo-Saxon practice, typically exclude changes in general market conditions. They also exclude legislative or regulatory changes affecting the industry as a whole. Under that drafting, a general tariff is not enough for the buyer to walk away. However, a tariff that disproportionately hits the sector or the target’s main client can indeed trigger the clause.
Distinguishing between a generic sector-wide impact and a specific impact on the business is precisely what requires case-by-case analysis. Consequently, this is the reason why deals already at an advanced stage have undergone price renegotiations or adjustments to their warranty structures.
The Clause Many Contracts Don’t Have
There is a third problem, perhaps the quietest one: contracts that simply have no provision for this kind of scenario. Distribution agreements, agency agreements, long-term supply contracts, technology licenses, and service agreements with US counterparts — signed without price-revision clauses, without hardship mechanisms, and without a precise definition of what constitutes force majeure.
Within the Spanish business fabric, especially among the mid-sized companies that made the leap abroad over the past decade, this contractual profile is common. These contracts were signed during a cycle of global commercial stability. Moreover, they were signed on the implicit assumption that the rules of international trade would not change disruptively. That assumption no longer holds. Contracts signed from now on must include explicit provisions: price-revision clauses tied to tariff changes, mandatory renegotiation mechanisms with defined deadlines, and precise definitions of which events trigger the agreed protections.
Spain as a Platform: The Other Side of the Coin
It is worth keeping sight of the positive side. Spain today operates as an investment platform with structural advantages: access to European, African, and Latin American markets, relative stability compared to transatlantic volatility, and a position that IESE has ranked as the world’s fifth-largest recipient of foreign direct investment in 2025. For non-European companies seeking to operate in Europe without direct exposure to EU-US friction, Spain is a natural destination.
On the other hand, this is creating corporate opportunities: joint ventures with investors from third countries seeking a gateway into Europe, intermediate holding structures, and the acquisition of Spanish companies by non-European buyers who view them as geostrategic assets. Every transaction carries its own map of legal risks, including the foreign investment screening regime under Law 19/2003 and Royal Decree 571/2023, which requires careful structuring from the outset.
Now Is the Time to Review Contracts
Tariff uncertainty will not be resolved before autumn 2026, when the bilateral EU-US summit is scheduled to take place in Washington. However, although the 15% agreement has reduced the worst of the risk, CEOE itself has warned that it remains open to arbitrary changes.
Companies with international contracts in force and corporate transactions underway should be doing two things. First, reviewing their contracts to identify what protections they have against tariff-related disruptions. Second, ensuring that deals under negotiation incorporate drafting suited to this new environment.
The combination of US tariffs and M&A has turned what was a macroeconomic risk into a specific contractual risk. Consequently, that makes it a legal problem by definition.
Firms that advise on corporate transactions and internationalization with a presence in the most active markets — including those in the Gulf, which are taking advantage of this reconfiguration of global trade to position themselves as alternative platforms — are paying particular attention to contract structure. This is an environment that no longer tolerates unreviewed standard clauses.
Contract law is not a formality. In this cycle, it is a competitive advantage.
Rafael López-Diéguez Piñar, Managing Director of RLD.
