When you give your factory a mold, a die, or a design file for free, customs does not treat it as a favor. It treats it as part of what you paid for the goods, and it expects duty on that value too.
What counts as an assist
An assist is anything you supply, directly or indirectly, free of charge or at reduced cost, for use in producing the imported merchandise. The classic examples are molds, dies, jigs, and tooling, but the definition is wider: engineering and design work done outside the US, artwork, and even materials or components you provide to the factory all count.
The key trigger is that the item is used in production of the imported goods. A laptop you lend a supplier for email does not count. The steel mold that stamps your product's housing absolutely does. Design files sent to the factory for manufacturing count; general market research does not.
Assists also catch indirect supply. If you pay a third party to make tooling and have it shipped to your factory, that is still your assist. CBP looks at who bore the cost, not whose name is on the shipping label.
Why importers miss them
Most Shopify brands discover assists during a CBP audit, not before. The product team bought the mold two years ago and capitalized it as equipment. The sourcing team negotiated the unit price down because the factory did not have to build tooling. Nobody connected the two, so the entry declared only the per-unit price.
The miss is expensive because assists are easy for CBP to spot in hindsight. The factory's quote will often break out tooling as a separate line, or your own books show a tooling payment to a vendor in the same country. An auditor reconciling your purchase orders against your entries will find the gap in an afternoon.
There is also a common misconception that assists only matter for big-ticket tooling. A set of design files you emailed for free has a value too: what you paid the designer. If the design work was done outside the US and you provided it to the factory, it is an assist regardless of the dollar amount.
How to value an assist
Valuation depends on what the assist is and where it came from. If you bought the mold from an unrelated seller, the assist value is what you paid for it. If you made it yourself or bought it from a related party, the value is its cost of production. For design and engineering work performed outside the US, the value is what it cost to produce, or what you paid for it.
The assist value gets apportioned across the imported merchandise. If a $12,000 mold produces 60,000 units, each unit carries $0.20 of assist value added to its dutiable price. You can apportion over the first shipment, over the number of units produced before the mold wears out, or over the entire production run, as long as the method is reasonable and documented.
Repairs and modifications to the assist count too. If you pay $2,000 to refurbish the mold mid-production, that cost joins the assist value. Keep a running ledger per tool: original cost, repairs, and the units apportioned so far.
How to declare assists on the entry
Assists are declared as an addition to the price actually paid or payable. Your broker adds the apportioned assist value to the unit value on the entry, so duty is calculated on the full dutiable value. This is not optional paperwork; failing to declare a known assist is a material omission.
The practical setup is a per-SKU assist schedule shared with your broker. For each SKU, list the assists involved, the total assist value, the apportionment method, and the per-unit addition. Update it when tooling is repaired, replaced, or retired, and send the updated schedule before the next shipment sails.
If you discover an undeclared assist from prior entries, prior disclosure is the fix. Disclosing before CBP starts an investigation caps your penalty exposure and shows reasonable care. Quietly adding assists to future entries while leaving past ones alone is the worst option: it creates a paper trail of the correction without the protection of the disclosure.
A simple assist process for small teams
You do not need a trade compliance department to handle assists. You need one spreadsheet and one habit. The spreadsheet lists every mold, die, design file, and component you have ever supplied to a factory, with its cost and which SKUs it touches. The habit is checking that spreadsheet before every new product launch and every tooling purchase.
Make the product team own the list, because they are the ones buying tooling. Make finance own the valuation, because they know what was paid. Make the broker the consumer of the output, because they declare it. Three owners, one spreadsheet, reviewed quarterly.
Handled this way, assists become a routine landed-cost input instead of an audit surprise. The duty on a properly declared assist is usually small. The penalty on an undeclared one never is.
Frequently asked questions
Do I owe duty on design work I did in-house in the US?
US-based design work is excluded from the assist definition. Keep timesheets or invoices showing the work location.
What if my factory built the tooling itself and charged me for it in the unit price?
Factory-built tooling reflected in the unit price is not an assist. Verify how the quote breaks out tooling costs.
Can I apportion a mold's cost over future production I have not ordered yet?
Yes, with a reasonable documented method applied consistently across entries.
I found an undeclared mold from last year's entries. What now?
File a prior disclosure: pay back duties plus interest now to cap penalty exposure.