Trade‐Policy Exposure and Managerial Adjustment Margins: Regime‐Dependent Evidence From Corporate Tax‐Base Outcomes

Trade‐policy shocks raise visible operating pressure on firms through sourcing costs, supplier exposure, and market‐serving choices. A direct operating‐margin interpretation points to production reconfiguration, pricing changes, or supply‐chain adjustment. The observed tax‐base pattern is less direct: Before the Tax Cuts and Jobs Act, greater tariff exposure tracks a wider corporate tax gap, while the same trade‐tax relation is largely muted after 2018 even as tariffs become more salient. This paper uses that contrast to study how trade pressure appears in both operating and internal tax‐base margins across policy regimes. The analysis uses a quarterly panel of U.S. Fortune 1000 firms from 2010Q1 to 2024Q4 to estimate the tariff‐gap relation, its post‐TCJA attenuation, and its variation with geographic segment diversity. The evidence distinguishes a visible trade‐pressure shock from a less visible tax‐base outcome. The trade‐tax relation is stronger among firms with broader geographic segment diversity, and the post‐TCJA regime break narrows the margin through which that relation appears. A calibrated policy mapping then traces how these firm‐response margins shift scenario‐implied statutory rates under different revenue and capital‐retention priorities.