(Yahoo! Finance) - The ever-increasing complexity of the US tariff landscape has been in evidence for months, but the dawn of 2026 provides a direct measure of just how much additional paperwork US importers must wade through one year into Trump 2.0.
The benchmark of tariff complexity is the so-called tariff book — formally known as the Harmonized Tariff Schedule of the United States — which is the central reference point for importers on what they have to pay the government.
The "basic" version for 2026 was just released and clocks in at over 4,500 pages. That's more than 100 pages longer than last year (and an 800-page increase from 2017, when Trump first took office).
It's just one indicator of the increased complexity that comes with a large dash of uncertainty for businesses so far in 2026 as the Supreme Court weighs how much of this new maze of regulations will pass legal muster.
The looming Supreme Court decision, which could be handed down as soon as Friday morning, is already presenting market risks. The complexity issue comes in addition to the tariffs themselves, which the Yale Budget Lab calculates at an average rate for consumers of 16.8%.
Where the most new tariff complexity lies
Businesses, as well as the ports where tariffs are calculated, have long argued that the complexity of tariffs — in addition to the costs of paying them — are an increasingly significant burden.
Scott Lincicome, a vice president at the Cato Institute's Trade Policy Studies department, took a deep look at the complexity issue late last year and found that "navigating the U.S. tariff system has gone from relatively easy to mind-numbingly difficult," with an economic cost for business that "is likely staggering."
He calculates that 17 different tariff measures now apply to significant US imports and must be accounted for — up from three in 2017.
Many of the changes seen over the past year can be found in Chapter 99 of the tariff book, which begins on page 3,320 and is focused on "temporary modifications established pursuant to trade legislation."
In other words: Trump's flurry of executive moves this past year.
Goods of every variety — ignition coils, hydraulic backhoes, and countless others — are painstakingly listed in the document and linked to a statistical reporting number, which then correlates to different rates.
Lincicome noted that the costs of paying tariffs themselves is plenty significant.
"Less discussed, however, is a regulatory burden that's at least as substantial," he said.
All eyes on the Supreme Court
Looming in the background is the Supreme Court decision on the legality of Trump's use of emergency tariff powers. A decision in either direction could jolt financial markets.
The case is known as Learning Resources, Inc. v. Trump and centers on a 1977 law called the International Emergency Economic Powers Act (IEEPA), which gives the president the ability to declare an economic emergency and take action but doesn't specifically outline tariffs as a remedy.
At stake in the decision is government revenue that so far is in the neighborhood of $100 billion. The US government has collected over $200 billion in duties since the start of 2025, and the Tax Foundation estimates about 55% of that revenue has been coming through these legally questionable tariffs.
In the meantime, plenty of the tariff complexity is here to stay, no matter what. Not under scrutiny by the Supreme Court are duties Trump has imposed based on other laws, most notably tariffs on sectors from steel to autos to furniture to lumber, which make up the remaining 45% of tariff revenue last year.
A negative decision for Trump could mean hundreds of entries in the tariff book will need to be quickly adjusted — the document saw more than 30 revisions over the course of 2025 — leading to additional headaches for businesses in the short term, with Trump's team promising to quickly replace the blanket tariffs if the Supreme Court strikes them down.
There's also the question of refunds. The Supreme Court could order billions returned if it determines the duties were collected illegally. Companies have been preparing for refunds since the arguments in November, even amid uncertainty about the result.
Costco (COST) made headlines recently when it became the biggest name to join the ranks of businesses preemptively suing the Trump administration to ensure their future eligibility for refunds.
But all sides see a messy process ahead. Henrietta Treyz of Veda Partners advised clients this week that any forthcoming refund process could be challenging.
"The queue for refunds will be long, involve myriad lawsuits and will be unlikely to result in one swift lump sum fiscal boon to domestic businesses, even if SCOTUS strikes them down," Treyz wrote in a note.
By Ben Werschkul - Washington Correspondent
