HS codes are 6 digits, universal across 200+ economies. HTS codes are 10 digits, US-specific, and they're the ones that determine your actual US duty rate. Show up at CBP with only an HS code and the entry gets rejected. The HTSUS (Harmonized Tariff Schedule of the United States) has about 17,000 active 10-digit lines in the 2026 edition, and picking the wrong one is the most expensive mistake in customs. Penalties run up to 4x the underpaid duty for fraud.
Quick Definition: HS vs HTS
HS (Harmonized System) is the 6-digit global product nomenclature maintained by the World Customs Organization. 183 member economies use it as the base for their tariff schedules, which means the first 6 digits of any US import code match what a Chinese exporter or a German broker uses. HTS (Harmonized Tariff Schedule of the United States) is the US extension — it takes the HS 6 and adds four more digits to make a 10-digit code. Published by the US International Trade Commission, updated roughly quarterly. Think of HS as the global root and HTS as the US-specific branch. Every HTS code starts with a valid HS code.
Digit-by-Digit Breakdown
Take HTS 8471.30.0100 (portable computers weighing ≤10 kg) as the worked example. Digits 1-2 (84) = Chapter: nuclear reactors, boilers, machinery. Digits 3-4 (71) = Heading: automatic data processing machines. Digits 5-6 (30) = Subheading: portable ADP machines weighing ≤10 kg. Those first six digits are the HS code — identical in China, Germany, Japan, and every other WCO member. Digits 7-8 (01) = the US tariff rate line, which sets the specific duty rate. Digits 9-10 (00) = the statistical suffix, used by Census for trade data reporting but not for duty assessment.
Why the US Uses a 10-Digit Code
The 6-digit HS isn't granular enough for US tariff policy. The government wants different rates for products that share an HS but differ by material, function, or end use. Example: HS 6204.62 covers women's cotton trousers globally. HTS breaks that out by whether the cotton is corduroy vs. other weaves, whether the garment is industrial, whether it meets specific construction rules — each variant gets its own 10-digit HTS with its own duty rate. The statistical suffix (digits 9-10) lets Census track specific sub-segments without changing the duty rate. That's why Census maintains a parallel 10-digit Schedule B for exports — same structural logic, different last four digits.
Worked Example: Same HS, Three Different HTS Codes
Men's cotton dress shirts all classify under HS 6205.20 globally. In the US they split: HTS 6205.20.2010 (certified hand-loomed and folklore, 19.7% MFN), HTS 6205.20.2050 (other, not napped, 19.7%), HTS 6205.20.2066 (napped, 19.7%). The MFN rate happens to match, but Section 301 coverage, trade agreement eligibility, and quota treatment differ by 10-digit line. On a $50,000 shipment, misclassifying a USMCA-eligible shirt as a non-qualifying line costs you the full 10% Section 122 — $5,000 you shouldn't have paid. CBP audits routinely catch these and charge back the difference plus interest, sometimes plus penalties up to 4x the underpaid duty.
Which Code Do You Actually Use?
US import entry on CBP Form 7501: full 10-digit HTS. Non-negotiable — an entry with fewer digits gets rejected or held. US export declaration via AES: 10-digit Schedule B, maintained by Census. Same HS 6 as imports, but digits 7-10 can differ. International commercial invoices: 6-digit HS is fine and recommended for clarity with foreign customs. USMCA, CPTPP, and most FTA origin certificates: typically 6-digit HS, sometimes 8. Rule of thumb — use the 10-digit HTS for anything touching CBP, and the 6-digit HS for everything else. Don't let a foreign supplier put their country's 8-digit code on your US entry. It won't map.
How to Look Up the Right HTS Code
Start with the USITC HTS search at hts.usitc.gov — authoritative, free, updated monthly. Cross-reference with CBP's CROSS database at rulings.cbp.gov, which holds 300,000+ binding and non-binding classification rulings that settle borderline cases. For high-value products or ambiguous classifications, file a Binding Ruling request with CBP under 19 CFR 177. It's free, takes 30-90 days, and locks CBP to a specific classification for that product — making it the gold standard for expensive or repeat shipments. High-volume importers use commercial classification tools (Descartes, Avalara, Thomson Reuters Onesource) that automate based on product descriptions. Garbage in, wrong HTS out — the automation is only as good as the source data.
Common Classification Mistakes That Cost Money
First: trusting a supplier-provided HTS without verifying. Chinese and Vietnamese factories routinely guess — they don't file US entries and don't know the HTSUS rate structure. Their 'best guess' can cost you 10-20 percentage points in duty. Second: classifying by what the product looks like instead of by essential character or primary function. A USB desk lamp might sit in Chapter 94 (lamps) or Chapter 85 (electrical articles) depending on design and marketing. Third: ignoring Chapter 98 provisions — US goods returned, temporary imports, personal effects — which can reduce or eliminate duty on eligible goods. Fourth: missing Section 301 and Section 232 exclusion lists tied to specific 8-digit HTS subheadings, or ignoring the difference between 'parts of' headings and the underlying article heading.
2026 HTSUS Updates to Watch
Revision 9 (February 2026) reflected the Section 122 10% tariff structure and the post-SCOTUS removal of IEEPA surcharges. USTR announced new Section 301 investigations on March 11, 2026 — if completed by the July 20 deadline, new HTS-specific surcharges will hit Chapter 99 subheadings. Canadian softwood lumber and Chinese solar products saw updated CVD rates in March. Expect another HTSUS revision by August 2026 once Section 122 expires on July 24 and Congress decides what replaces it. If you import from China, check Chapter 99 every month — that's where the temporary Section 301 and Section 232 surcharges live, and rates change without much notice.
Key Takeaway
HS is the global 6-digit root. HTS is the US 10-digit extension that drives your actual duty rate. For any US customs entry, you need all 10 digits — the first 6 are shared with the rest of the world, the last 4 are where US-specific rates and statistics live. Misclassification is the most common and most expensive customs mistake. CBP charges back underpaid duties with interest, negligence penalties run up to 2x the shortfall, and fraud penalties can reach 4x the duty or the full value of the goods. Use hts.usitc.gov and file a Binding Ruling when in doubt.
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