The Budget Lab’s goal is to bring fresh ideas and new methods so policymakers can make better choices. To that end, they build tools to analyze government policies' fiscal and social impacts.

One such is its Tariff Rate Tracker, a newly deployed open-source platform that brings unprecedented transparency to the rapidly changing U.S. tariff landscape. Developed in response to more than forty tariff-policy revisions since early 2025, the tool calculates daily effective tariff rates (ETRs) using official U.S. International Trade Commission Harmonized Tariff Schedule data and provides detailed estimates by product, country, sector, and legal authority.

The tracker addresses a growing challenge for economists, policymakers, businesses, and researchers: understanding the real-world impact of overlapping tariff regimes whose effects can change from day to day. Starting from a baseline U.S. tariff rate of less than 3 percent, the Budget Lab's analysis shows effective rates surged above 22 percent during major policy actions before declining as trade agreements, legal rulings, and policy revisions took effect.

A key innovation is the tool's ability to model how multiple tariff authorities interact. It automatically applies complex "stacking" rules, allowing users to decompose tariff burdens by policy source and conduct simulations of alternative trade-policy scenarios. The platform's code, data pipeline, and assumptions are publicly available through GitHub, supporting reproducible research and independent analysis.

For The Budget Lab, this project exemplifies how advanced computing and data-intensive analysis can transform public-policy research. Leveraging Yale's research computing infrastructure, the team has created a dynamic resource that helps decision-makers track, understand, and evaluate the economic consequences of evolving U.S. trade policy.