UN38.3 is the set of design type tests in part III, sub-section 38.3 of the UN Manual of Tests and Criteria that every lithium cell and lithium battery type must pass before it can move as cargo. In U.S. law the requirement sits in 49 CFR 173.185, the section of PHMSA‘s Hazardous Materials Regulations on lithium cells and batteries, which applies to shipments by air, vessel, highway and rail. It covers loose cells, battery packs and the batteries inside a flashlight, a bike light, a set of earbuds or an e-bike.
For importers of electronics, LED lighting and bike gear, UN38.3 is not a customs filing. CBP does not ask for it at entry. It is a transport document problem that surfaces earlier: a forwarder or carrier that will not book the freight, a foreign shipper that cannot produce a test summary, or a pallet of power banks that cannot legally move inland after it lands. The fix is contractual. The importer has to make the test summary a deliverable of the purchase order, check it against the product that actually ships, and give its forwarder the information the regulations say an importer owes.
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The Eight UN38.3 Tests and What Each One Proves
Under 49 CFR 173.185(a)(1), each lithium cell or battery must be of a type proven to meet the criteria in sub-section 38.3 of the UN Manual of Tests and Criteria. The edition incorporated by reference in 49 CFR 171.7 is the Seventh revised edition (2019) with Amendment 1 (2021). Types tested to Revision 3, Amendment 1 or any later revision applicable on the date of type testing can continue to be transported; types that only met Revision 3 are no longer valid, except cells and batteries made to such types before July 2003.
PHMSA described the logic of the test series in its January 11, 2010 lithium battery final rule: the altitude simulation, thermal, vibration and shock tests simulate extremes a battery can meet in transport, and the external short circuit, impact, overcharge and forced discharge tests are included because those conditions contribute to short circuits and other hazards. Comparing the battery before and after testing is meant to catch leakage, abnormal venting, disintegration, cracking, swelling or any sign of an internal short circuit. The eight tests are:
- Altitude simulation
- Thermal test
- Vibration
- Shock
- External short circuit
- Impact (impact or crush)
- Overcharge
- Forced discharge
Tested Cells Do Not Make a Tested Battery
Section 173.185(a)(1) states that batteries are subject to the tests regardless of whether the cells used to build them are of a tested type. A pack assembled in Shenzhen or Ho Chi Minh City from cells that passed UN38.3 still needs its own battery-level test, and a new pack design, a different cell supplier or a change in cell count can mean a new type. A single-cell battery is treated as a cell.
The practical consequence for a buyer: a test summary for the cell is not a test summary for the pack inside your product. Ask for the one that names the battery or product model you are buying.
The UN38.3 Test Summary: Required Content and Who Must Provide It
Two different documents come out of testing. Under 173.185(a)(2), the manufacturer must create a record of satisfactory completion of the tests, such as the full test report, before offering the battery for transport, keep it for as long as the design is offered for transport and one year after, and make it available to federal, state or local government on request. The full report usually stays with the manufacturer.
The document that travels down the supply chain is the test summary. Section 173.185(a)(3) requires each manufacturer and each subsequent distributor of lithium cells or batteries made on or after January 1, 2008 to make a test summary available. The only exclusion is button cells installed in equipment, including circuit boards. A U.S. importer that resells the batteries, or products containing them, is a subsequent distributor in that chain and needs a summary it can pass on.
The rule lists the elements. A summary missing any of them is not compliant, and in practice it is usually the first thing a dangerous goods desk rejects.
| Element | What to check on the document |
|---|---|
| Manufacturer name and contact | Address, telephone, email and website of the cell, battery or product manufacturer |
| Test laboratory | Lab name with address, telephone, email and website |
| Report identification | A unique test report ID number and the date of the test report |
| Battery description | Lithium ion or lithium metal, mass, watt-hour rating or lithium content, physical description, and cell, battery or product model number |
| Tests and results | List of tests conducted with pass or fail, plus reference to assembled battery testing if applicable |
| Manual edition | The revised edition of the UN Manual of Tests and Criteria used, and any amendments |
| Responsible person | Name and title of the person vouching for the information |
Batteries Contained in or Packed With Equipment vs Standalone Cells
Most importers in this vertical do not buy loose batteries. They buy a product with a battery inside or a battery in the same box. The regulations treat those three cases differently, and the UN number on the lithium battery mark tells the carrier which case it is handling. Under 173.185(c)(3)(i), lithium ion cells or batteries shipped alone are UN3480 and lithium metal are UN3090; when contained in or packed with equipment they become UN3481 or UN3091.
The UN38.3 obligation does not change between the three. A battery sealed inside a bike headlight or a pair of wireless earbuds still has to be of a tested type, and the test summary still has to exist. What changes is packaging, marking and how much the shipment can benefit from the smaller-battery exceptions.
Under 173.185(c)(1), a lithium ion cell up to 20 Wh, a lithium ion battery up to 100 Wh, a lithium metal cell with up to 1 g of lithium and a lithium metal battery with up to 2 g qualify for the smaller-battery exceptions from much of the hazard communication and UN specification packaging. Since May 10, 2024, every lithium ion battery must also show its watt-hour rating on the outside case under 173.185(a)(5). An e-bike pack well above 100 Wh is fully regulated as Class 9 cargo; a flashlight with a small cell inside often is not, but it still needs a tested battery type.
Two other provisions matter for product companies. Low production runs of not more than 100 cells or batteries a year and prototypes shipped for testing are excepted from the testing requirement under 173.185(e), but only with Packing Group I packaging, a shipping paper notation and, for air, cargo aircraft with prior approval. Damaged, defective or recalled batteries can move only by highway, rail or vessel with the special packaging in 173.185(f). How these rules play out on aircraft, and the state-of-charge limits, are covered in our guide to lithium battery air shipping.
What a US Importer Must Hold Before Booking Ocean or Air Freight
The Hazardous Materials Regulations put a specific duty on the importer. Under 49 CFR 171.22(f)(1), each person importing a hazardous material into the United States must provide the shipper, and the forwarding agent at the place of entry, timely and complete written information on the HMR requirements that apply to the shipment. The shipper, directly or through that forwarding agent, then gives the first U.S. carrier the shipper’s certification, and a carrier may not accept hazardous material without it unless the shipment is excepted. Shipping papers and markings must be in English.
In other words, the regulation assumes the U.S. buyer knows what it is bringing in and tells its overseas supplier and its forwarder. For an importer of electronics, LED products or bike gear that translates into a short file per SKU, assembled before the first booking rather than when a carrier asks.
- The UN38.3 test summary for the exact battery or product model, with all 173.185(a)(3) elements.
- The battery’s chemistry, watt-hour rating or lithium content and mass, matching the summary and the marking on the case.
- The configuration: battery alone, packed with equipment or contained in equipment, which sets the UN number.
- The safety data sheet or equivalent product information the forwarder’s dangerous goods desk asks for.
- Written confirmation from the supplier that the pack design, cell source and cell count have not changed since testing.
- For prototypes or small runs, documentation supporting the 173.185(e) exception.
What Happens When the File Is Missing
A shipment with no valid test summary usually fails before it moves: the forwarder declines the booking or the origin carrier refuses the cargo. Landing the goods does not solve it, because 173.185 applies to every mode, including the truck that takes the pallet from the port to your warehouse.
PHMSA‘s civil penalties under 49 CFR 107.329 reach $102,348 per violation for a knowing violation, $238,809 where it results in death, serious illness, severe injury or substantial destruction of property, and each day of a continuing violation is a separate offense. Those figures apply to whoever offers or causes the hazardous material to be transported, which can include the importer that arranged the move.
Tariff Lines for Lithium Cells, Packs and Battery-Powered Goods
UN38.3 compliance does not change the duty, but the same SKUs carry some of the steepest stacked rates in the tariff schedule when they come from China. The table shows typical lines for this vertical with the MFN rate from the Harmonized Tariff Schedule and the additional duties our engine applies as of October 28, 2026: the China Section 301 lists, the four-year review increase on lithium-ion batteries effective January 1, 2026, and the Section 301 forced labor duty of 12.5% in effect since July 24, 2026, with its note 52(b) exemptions. For a full background on the forced labor action, see our guide to Section 301 forced labor tariffs. You can run your own lines in the China to US tariff calculator or the Vietnam to US tariff calculator.
| HTS | Product | MFN | China additional | China total | Vietnam total (MFN + 12.5%) |
|---|---|---|---|---|---|
| 8507.60.00 | Lithium-ion batteries (packs, power banks, e-bike packs) | 3.4% | 37.5% (four-year review 25% + forced labor) | 40.9% | 15.9% |
| 8506.50.00 | Lithium primary cells and batteries | 2.7% | 37.5% (List 1 + forced labor) | 40.2% | 15.2% |
| 8513.10.20 | Flashlights | 12.5% | 12.5% (forced labor only) | 25% | 25% |
| 8512.10.20 | Lighting equipment of a kind used on bicycles | Free | 20% (List 4A + forced labor) | 20% | 12.5% |
| 8711.60.00 | Cycles with an electric motor for propulsion (e-bikes) | Free | 37.5% (List 2 + forced labor) | 37.5% | 12.5% |
| 8518.30.20 | Headphones and earphones, other | Free | 12.5% (forced labor only) | 12.5% | 12.5% |
| 8471.30.01 | Laptops and other portable data processing machines | Free | 0% (exempt under note 52(b), not listed) | 0% | 0% |
Notes on the Table
Totals are MFN plus additional duties and exclude antidumping and countervailing duties and any product exclusions. Heading 8507.60 is also enumerated in chapter 99 note 33(g) for parts of passenger vehicles and light trucks; a lithium-ion battery entered as a vehicle part falls under the Section 232 automobile parts duty instead, and goods covered by Section 232 are exempt from the forced labor duty. EV propulsion batteries are covered in our article on EV and battery tariffs.
The laptop line shows how much classification matters: a product whose battery is incidental can sit in a heading the forced labor action exempts, while a standalone power bank pays more than 40% from China. A HTS classification review is worth doing before the purchase order, not after the first entry.
Building UN38.3 Into the Supply Agreement
Because no agency checks UN38.3 at the border, the leverage point is the contract. Importers that rarely see battery problems write three things into their supplier terms: delivery of a compliant test summary for each battery or product model before the first shipment, notice of any change to cell supplier, chemistry, capacity or pack design, and retest at the supplier’s cost when a change creates a new type. They also keep the summaries on file where the forwarder can see them, because a subsequent distributor that cannot produce one has the same problem as the manufacturer.
Button cells are the one recurring gap. Coin cells installed in equipment are outside the test summary rule, but consumer products that contain button or coin cells carry separate CPSC obligations; see our guide to Reese’s Law for the CPSC side. For importers moving battery-powered products at volume, our retail and consumer goods customs brokerage team files the entry and can confirm the test summary is on file before cargo ships.
Frequently Asked Questions
What is UN38.3?
UN38.3 is the series of eight design type tests in part III, sub-section 38.3 of the UN Manual of Tests and Criteria that every lithium cell and battery type must pass before it can be transported. In the United States the requirement is in 49 CFR 173.185(a)(1) and applies to air, vessel, highway and rail shipments.
Who has to provide a UN38.3 test summary?
Each manufacturer and each subsequent distributor of lithium cells or batteries made on or after January 1, 2008 must make a test summary available under 49 CFR 173.185(a)(3). The only exclusion is button cells installed in equipment, including circuit boards.
Does CBP check UN38.3 at import?
No. UN38.3 is a transport safety requirement enforced by PHMSA under the Hazardous Materials Regulations, not an admissibility requirement checked at customs entry. It is enforced by forwarders, carriers and PHMSA, and a missing test summary usually stops the shipment before it is booked.
Do batteries inside a product need UN38.3 testing?
Yes. Batteries contained in or packed with equipment must be of a type that passed UN38.3, the same as loose batteries. What changes is the UN number (UN3481 or UN3091 instead of UN3480 or UN3090), the packaging and which smaller-battery exceptions apply.
If the cells passed UN38.3, does the battery pack need testing?
Yes. 49 CFR 173.185(a)(1) states that lithium batteries are subject to the tests regardless of whether the cells used to build them are of a tested type. Ask the supplier for the test summary that names your battery or product model.
What must a US importer of lithium batteries tell its shipper?
Under 49 CFR 171.22(f), each person importing a hazardous material into the United States must give the shipper and the forwarding agent at the port of entry timely and complete written information on the HMR requirements that apply to the shipment. In practice that means the test summary, battery data and configuration for each SKU.
What is the duty on lithium-ion batteries from China?
As of October 28, 2026, lithium-ion batteries in HTS 8507.60.00 from China pay 3.4% MFN plus 25% under the Section 301 four-year review and 12.5% under the Section 301 forced labor action, a total of 40.9% before any antidumping, countervailing duty or exclusion. From Vietnam the same line totals 15.9%.
