Dec 1, 2025 – Costco files a lawsuit in the U.S. Court of International Trade seeking a full refund of the roughly $90 billion in IEEPA‑related tariffs it paid, arguing the tariffs are illegal and that a Supreme Court reversal would jeopardize its ability to recover the funds[25].

Dec 2, 2025 – Costco files a separate refund claim to secure a judgment before the Supreme Court’s decision, warning that Customs‑Border‑Protection’s Dec 15 liquidation deadline could close its refund window if the Court delays[23].

Dec 9, 2025 – President Trump posts on Truth Social that a Supreme Court ruling against his tariff program would be “the biggest threat in history” to U.S. national security, insisting tariffs have “strengthened the economy and security” and warning of a “complete mess” if refunds become required[30][2].

Dec 26, 2025 – The Trump administration launches sweeping “global tariff wars,” imposing new duties on Canada, Mexico, China and raising steel/aluminum rates to 50 %, while also rolling out sector‑wide levies on autos, copper and kitchen cabinets[19].

2025 (overall) – U.S. tariff revenue jumps by about 200 % in 2025, with $187 billion more collected than in 2024, and 80 % of the burden falling on businesses, setting the fiscal backdrop for the legal fight[16].

Jan 1, 2026 – President Trump signs a proclamation delaying planned tariff hikes on upholstered furniture, kitchen cabinets and vanities until at least Jan 2027, keeping the existing 25 % rate in place[17].

Jan 3, 2026 – Treasury data show the 2025 tariff surge could push pass‑through to consumers up to 20 % in 2026, while Goldman Sachs estimates tariffs added 0.5 percentage point to inflation in 2025 and project another 0.3 point rise in the first half of 2026[16].

Jan 8, 2026 – Legal analysts warn the Supreme Court could strike down the Korea‑specific tariffs, dropping the 15 % rate to zero and forcing refunds of roughly $150 billion, jeopardizing the $350 billion investment pledge in the U.S.–Korea framework[28].

Jan 9, 2026 – The Supreme Court declines to issue a ruling on the reciprocal‑tariff case, extending uncertainty for businesses and keeping the 15 % Korea tariff in place[27].

Jan 12, 2026 – Trump warns on social media that a Court decision overturning his tariffs would create a “complete mess,” citing the impossibility of repaying billions of dollars in refunds[2][15].

Jan 14, 2026 – The Court again postpones any decision on the tariff legality, leaving the case unresolved as business leaders await clarification[26].

Jan 15, 2026 – South Korean Trade Minister Yeo Han‑koo says Seoul will monitor the U.S. ruling and craft an “optimal response,” noting a 50‑50 chance of the decision and preparing to use other U.S. authorities if IEEPA tariffs fail[14].

Jan 16, 2026 – Administration officials outline a backup tariff plan, including Section 301 authority and a 150‑day window, in case the Supreme Court invalidates the IEEPA‑based duties; USTR Jamieson Greer is heavily involved in drafting the contingencies[13].

Jan 20, 2026 – Trump tells reporters he “anxiously awaits” the Supreme Court’s ruling on the IEEPA tariffs, while the Court issues no decision that day, maintaining the status quo for the 15 % Korea tariff and the broader tariff program[10][12].

Jan 28, 2026 – The Court’s fast‑track schedule places oral arguments on Nov 5 and sets a possible opinion release around Feb 20; justices express skepticism about the tariffs’ legality, and experts expect a final decision by June 2026[9][8].

Jan 29, 2026 – In a Cabinet meeting, Trump warns that current tariffs are “already steep” and could become “much steeper,” emphasizing their national‑security benefits and pledging to preserve revenue even as the Supreme Court reviews the program[7].

Feb 4, 2026 – House Financial Services Committee ranking member Maxine Waters interrupts Treasury Secretary Scott Bessent, demanding “Can you shut him up?” and linking rising coffee, banana and lumber prices to Trump‑era tariffs, while Bessent cites San Francisco Fed data that tariffs do not cause inflation[5].

Feb 17, 2026 – USTR Jamieson Greer tells CNBC the administration may tweak how 50 % steel and aluminum duties are applied to ease compliance, confirms the tariffs remain “successful,” and says a new mechanism will replace them if the Supreme Court strikes them down[6].

Feb 18, 2026 – NEC director Kevin Hassett calls the New York Fed’s tariff‑impact paper “the worst paper I’ve ever seen in the history of the Federal Reserve system,” demands discipline for its authors, and notes the study finds 90 % of the tariff burden falls on U.S. firms and shoppers[1][4].

Feb 18, 2026 – President Trump nominates former Fed Governor Kevin Warsh to replace Jerome Powell, signaling a shift toward a more critical stance on Fed independence amid ongoing investigations into Powell and Governor Lisa Cook[4].

Feb 18, 2026 – The Federal Open Market Committee votes to keep interest rates unchanged in January as inflation eases, fueling debate over possible future rate cuts while the tariff dispute looms[1].

Future (by June 2026) – Legal scholars expect the Supreme Court to issue its final opinion on the IEEPA tariffs by June 2026, a decision that could reshape U.S. use of emergency economic powers and affect billions in tariff revenue and pending refund claims[8].

Future (post‑ruling) – If the Court invalidates the tariffs, the administration plans to invoke alternative authorities such as Section 301 or Section 338 to preserve a “continuity of the president’s trade policy,” according to USTR officials[6][13].