Assists in Customs Value: Moulds, Materials and Design You Supply to the Factory
The mould you paid for in China shows up in every part you import
A US power-tool brand has its drill housings made in Dongguan. To launch the line, it commissioned injection moulds from an independent Chinese toolmaker for $150,000, then handed them to the assembly plant at no charge. The housings land in Long Beach at $4.80 a unit. In the books, the moulds are a fixed asset depreciated over five years. On the entry summary, they do not exist.
That gap is one of the easiest for an auditor to find, because it sits in plain sight on the fixed-asset register: equipment located at a foreign supplier with no customs trail. Valuation law calls it an assist, and it requires its value to be added to the goods it helped produce.
This guide covers the four assist categories, how to value them, the three apportionment methods, and the exception that excludes design work depending on where it was done.
Four categories, one logic
The WTO Customs Valuation Agreement (Art. 8.1(b)), mirrored in 19 U.S.C. § 1401a(h), UK valuation rules and India's Rule 10(1)(b), covers goods and services the buyer supplies directly or indirectly, free of charge or at reduced cost, for use in producing the imported goods, to the extent their value is not already in the invoice price. The reasoning: had the seller sourced these items itself, it would have charged for them. Customs rebuilds the full price.
| Category | Typical examples | Special condition |
|---|---|---|
| (i) Materials and components incorporated | Fabric, chips, zippers, branded labels | None: always added |
| (ii) Tools, dies, moulds | Injection moulds, cutting dies, jigs | Added wherever the tool is located |
| (iii) Materials consumed in production | Catalysts, abrasives, test chemicals | Used up during production |
| (iv) Engineering, design, plans | Technical drawings, CAD files, artwork | Only if done outside the importing country |
Assists sit alongside the other statutory additions and only matter once transaction value is the applicable method. They differ from royalties and licence fees in kind: something supplied, not a sum paid.
Valuing the assist, then spreading it
CBP regulations (19 C.F.R. § 152.103(d)) and the WTO interpretative note set the same rules. An assist bought from an unrelated party is valued at its acquisition cost. One produced by the importer or a related party is valued at its cost of production. One previously used is adjusted downward for that use. In every case, the cost of transport to the place of production is added: fabric bought in Italy and shipped to a factory in Bangladesh counts at price plus freight.
A single amount must then be spread over many entries. Three methods are accepted, at the importer's choice, provided it is documented and applied consistently:
- Full value on the first shipment: simple, but it loads all the duty onto one container.
- Spread over units produced up to the first shipment: rarely useful for long runs.
- Spread over the entire anticipated production: the most even, provided contracts or firm commitments support the forecast; a large gap between forecast and actual justifies resetting the rate.
Three edge cases come up repeatedly. An assist supplied at reduced cost is added only for the difference: if you sell fabric to the factory at half its cost, the other half is the addition. A used mould moved to a new supplier is valued net of its prior use, ideally on the depreciation schedule already in your books rather than an improvised estimate. And tooling the seller pays for and recovers through a higher unit price is already in the invoice, so nothing is added twice, provided the contract shows it.
The real difficulty is information, not arithmetic. Procurement knows a mould was funded; the customs broker does not. A per-SKU assist register, sent to the broker with each unit price, closes that gap.
Same rules everywhere, one border that changes everything for design
The text is WTO-derived and close to identical across markets. The decisive difference is category (iv): design is added only when undertaken outside the country of importation.
| Market | Legal basis | Design not added if done in… | Look-back |
|---|---|---|---|
| United States | 19 U.S.C. § 1401a(b)(1)(C), (h) | the US | 5 years (19 U.S.C. § 1621) |
| United Kingdom | Valuation rules retained after Brexit | the UK | Generally 3 years |
| European Union | UCC Art. 71(1)(b) | the EU | 3 years (UCC Art. 103) |
| India | Rule 10(1)(b), Customs Valuation Rules 2007 | India | Section 28, Customs Act 1962 |
Three worked cases
1. US drill housings, spread over the run. Moulds bought for $150,000, anticipated production of 300,000 units under contract, 100,000 imported in year one. Combined rate of 28.7% (3.7% MFN plus 25% Section 301) used as a working assumption; verify against your HTS line.
Assist per unit = $150,000 / 300,000 = $0.50
Year-one addition = 100,000 x $0.50 = $50,000
Additional duty = 28.7% x $50,000 = $14,350
MPF at 0.3464% also applies to the added value, within the per-entry cap
2. UK footwear, the same design in two cities. A UK brand pays £80,000 for a collection design, produced in Vietnam, 40,000 pairs anticipated. Duty of 8% used as an illustrative rate; check your commodity code and any preference.
Designed by the London studio → addition = £0
Designed by the group's Hong Kong studio → addition = £80,000 (£2.00 a pair)
Additional duty = 8% x £80,000 = £6,400; import VAT on top, recoverable
3. India, a used die sent to Thailand. A Pune auto-parts importer ships a die it built in-house to its Thai supplier. BCD of 15% used as a working assumption before any FTA preference.
Cost of production ₹1.2 crore, less 40% for prior use = ₹72 lakh
+ freight to Thailand ₹3 lakh → assist = ₹75 lakh
BCD 15% = ₹11.25 lakh; SWS 10% of BCD = ₹1.125 lakh
Non-creditable duty cost = ₹12.375 lakh; IGST creditable
Price the assist before an auditor does
Add the per-unit share of tooling or materials to your unit value and compare duties and taxes with and without it.
Run the numbers →Your fixed-asset register is exhibit A
Three habits cover most of the exposure. Reconcile, every year, the list of assets held at foreign suppliers against your entries: any mould with no customs trail is a missing addition. Pick an apportionment method per tool, write it down, and send it to your broker with the unit value. And record where each piece of design work was done, because the same invoice is either nothing or fully dutiable depending on the city. These are the first questions in a post-clearance audit, and a current register turns that conversation into a check rather than an assessment.
Frequently asked questions
We paid the tooling charge directly to the supplier on a separate invoice. Is that an assist?+
Strictly speaking no, but it is still dutiable. A tooling charge paid to the seller of the goods is part of the price actually paid or payable, even when invoiced separately and at a different time, so it is added to the value of the parts. The assist rules cover the other scenario: the buyer supplies the mould itself, bought from an independent toolmaker or made in-house. Either way the mould ends up in the dutiable value; only the legal route differs.
Our mould never leaves China. Why would it be dutiable in the US?+
Because customs is not taxing the mould, it is taxing the parts the mould made. Under 19 U.S.C. § 1401a(b)(1)(C), the value of any assist is added to the transaction value of the imported merchandise, wherever the tool physically sits. The mould does not cross the border; its value does, spread across each shipment of parts.
Is design work done by our in-house team in the US or UK an assist?+
No. Engineering, development, artwork, design work and plans are only assists when undertaken outside the country of importation: outside the United States for US entries (19 U.S.C. § 1401a(h)(1)(A)(iv)), outside the UK for UK entries, outside India under Rule 10(1)(b)(iv). The same drawings produced by a group studio in Shenzhen or Ho Chi Minh City must be added. Research and preliminary sketches are generally not covered.
Which apportionment method should we choose?+
CBP (19 C.F.R. § 152.103(e)) and the WTO interpretative note accept three: the full value on the first shipment, spread over units produced up to the first shipment, or spread over the entire anticipated production where contracts or firm commitments exist. Anticipated production gives the most even duty profile. Whatever you pick, document it and apply it consistently; switching mid-run to shrink the base is exactly what an audit flags.
What if we never declared assists on past entries?+
In the US, undeclared assists can trigger penalties under 19 U.S.C. § 1592, with a five-year statute of limitations. A prior disclosure under 19 C.F.R. § 162.74, filed before CBP opens an inquiry, typically reduces the penalty to interest on the unpaid duty for negligence cases. In the UK, HMRC can generally assess duty for up to three years, and voluntary disclosure is treated more favourably than discovery during an audit.
Marie Fontaine
Marie leads customs research at TRADE-COST. She spent eight years in tariff classification and post-clearance audits before joining the product team to turn customs expertise into software.
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