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Schedule B vs HTS Units of Quantity: Where the Two US Schedules Disagree

The same six-digit code can speak two dialects. Match every prefix Schedule B shares with the Harmonized Tariff Schedule and 743 of the 5,595 shared prefixes (13.3 percent) publish units of quantity that share no token at all — even after the friendliest possible vocabulary normalization. One of them is the set of codes your buyer quotes you; the other is the set AES demands on the export declaration. Here is the full census, the chapter hot spots, and the three-minute pre-flight that keeps filings out of rejection queues.

Schedule B and the HTS look like siblings because they are: both descend from the international Harmonized System, both describe physical goods, and both lean on the same ten-digit discipline. But they answer different questions. The HTS is an import instrument — its units of quantity feed duty computation, quota ceilings and statistical reporting on goods coming in. Schedule B is an export instrument, administered by the Census Bureau to build the US trade ledger, and its units feed the Electronic Export Information filing. Nothing in either regulation obliges the two vocabularies to agree, and — as this census shows — they frequently do not.

The census method: match the prefixes, normalize the words, compare

The comparison runs entirely at build time against our stored snapshots of both schedules, and it is deliberately conservative. Four steps:

1. Join key. Every Schedule B code and every dot-stripped HTS number is truncated to its first six digits — the level where both schedules still mean the same product family to the rest of the world.
2. Vocabulary normalization. HTS cells are split into their component units (a cell like No.; kg means the filer reports quantity in both units); tokens are lowercased, trailing periods are stripped, gm folds to g, and m2/“m²” fold together. Schedule B compounds such as NO/KG stay whole, exactly as published.
3. Population. A six-digit prefix enters the census when both schedules publish at least one non-empty unit for it.
4. Mismatch test. The prefix mismatches when the Schedule B unit set and the HTS unit set share zero tokens.

Disclosed limitations: slash compounds on the Schedule B side are not decomposed into their parts, and no synonym ladder beyond gm/doz/m² is applied — so the audited mismatch rate is an upper bound on true semantic disagreement, not a lower bound. A raw, case-sensitive comparison without any normalization puts effectively every shared prefix at odds, which is why the normalized figure is the honest planning number.

743 of 5,595 shared prefixes disagree on units

Both schedules publish about 5,619 (Schedule B) and 5,596 (HTS) distinct six-digit prefixes; 5,595 exist in both. After normalization, 743 prefixes — 13.3 percent — share no unit token at all. For those codes, the quantity column a buyer expects on a proforma invoice and the quantity column AES validates on the export declaration are drawn from disjoint vocabularies.

Source: data/scheduleb.json (Census Bureau sbsdf.zip snapshot, 2026-10-16T09:48:56Z) and data/hts.json (USITC REST export). Every figure on this page is recomputed from those files at generation time — nothing is hand-copied.

The mismatch load concentrates hard in manufactured-goods chapters. Chapters 61 and 62 alone contribute 210 of the mismatches. The top chapters by mismatch count are 61 (106), 62 (104), 52 (70), 55 (58), 54 (34), 63 (31). Textiles and apparel dominate because their quantity grammar is genuinely two-dimensional — pieces and kilograms, square meters and weight — and the two schedules disagree about which dimension leads. Chapter 98 warehouse and statistical codes, plus a handful of Schedule-B-only artifacts, sit outside this comparison entirely: 24 SB prefixes have no HTS counterpart at all (sample: 880000, 910111, 910199, 910211, 910219).

Worked examples: 6 prefixes, 6 standoffs

Each row below is pinned by the audited probe output. Read the last two columns as the practical collision: what the exporter's paperwork naturally says versus what the import-side schedule publishes for the identical product family.

Two patterns repeat across the full census. First, the compound-vs-simple standoff: HTS publishes a dual unit (No.; kg) while Schedule B keeps a compound token (no/kg) — semantically related but never token-equal, so strict comparisons flag them even though a human would call them close. Second, the vocabulary gap: liters versus L, dozens spelled differently, grams versus GM. The normalization step absorbs the spelling gap; it cannot absorb the structural one.

Pre-flight checklist before you quote a unit on the EEI

1. Find the Schedule B number first, then read its unit. Your classification may already be done — the Schedule B export codes guide walks the lookup. The unit printed beside the code is the one AES validates against.
2. Do not copy the HTS unit backwards. If your product lived on the import side (supplier datasheets, landed-cost sheets), its unit row came from the HTS. Check it against the export schedule instead of assuming symmetry — that assumption is precisely what the census above prices at 13.3 percent.
3. When units differ, report what the export schedule asks for. Compound requirements mean every listed component must carry a value; picking just one half of a dual unit is the classic rejection trigger. The ten-digit statistical suffix guide explains how the trailing digits interact with reporting detail.
4. Sanity-check quantities on both sides of the ocean. Run the same shipment through our HS code lookup and read the dual-unit census notes; where the two schedules disagree, document the conversion (pieces to kilograms, square meters to weight) once and reuse it on every filing.

Frequently asked questions

1. What is the difference between Schedule B and HTS units of quantity?

They answer different regulators. The HTS unit of quantity supports imports: duties, quotas and import statistics are keyed to it. Schedule B units support exports: they are what the Electronic Export Information filing must declare to the Census Bureau. Both schedules descend from the international Harmonized System, but each publishes its own unit vocabulary, and neither is obliged to mirror the other.

2. How many shared codes actually disagree on the unit?

After normalizing both vocabularies (lowercasing, stripping trailing periods, folding gm/g and m2/m²), 743 of the 5,595 six-digit prefixes shared by both schedules publish unit sets with zero overlap — 13.3 percent. Under a raw, case-sensitive comparison virtually every shared prefix differs, which is why the normalized figure is the meaningful one.

3. Why can't a computer just translate the units automatically?

Most of the gap is structural, not orthographic. 550 of the 743 mismatching prefixes carry a slash compound on the Schedule B side (no/kg, doz/kg, m2/kg) while the HTS publishes the same dimensions as a dual unit separated by a semicolon. Converting between 'report both' and 'report a ratio' is a business decision about which quantity your shipment can actually evidence, not a dictionary lookup.

4. Which product groups suffer the worst mismatches?

Manufactured goods dominate: knit and woven apparel (chapters 61 and 62) lead the census, followed by cotton fabrics, man-made filament fabrics, floor coverings and home linens. The common thread is two-dimensional quantity grammar — pieces plus weight, or area plus weight — where the two schedules disagree about which dimension is primary.

5. Will a unit mismatch get my export filing rejected?

It is among the most common AES validation errors, and the fix is cheap: report the unit exactly as the Schedule B (or, for some program filings, the HTS) record requires, including both halves of any compound requirement. When the two schedules disagree for your code, derive the export-side value from your own packing data and keep the conversion note on file — the census above tells you exactly when to expect the two schedules to diverge.

Where to check next

• Schedule B export codes guide
• HTS ten-digit statistical suffixes
• dual unit-of-measure census
• HS code lookup