HS Code for Small Power Transformers
The HS Code for small power transformers is 850431. The MFN duty rate for importing to the US is 2.4%.
| HS Code (6-digit) | 850431 |
|---|---|
| US Duty Rate (MFN) | 2.4% |
| EU Duty Rate (MFN) | 2.2% |
| Chapter | 85 |
| Heading | 8504 |
| Last Updated | 2026-05 |
Description
Transformers having a power handling capacity not exceeding 1 kVA
HS Code 850431 covers small power transformers not exceeding 1 kVA capacity, with a US MFN duty rate of 2.4%.
Frequently Asked Questions
Are there any specific energy efficiency labeling or registration requirements for importing small power transformers (HTS 850431) into the United States?
Yes, transformers under 1 kVA imported into the U.S. must comply with the Department of Energy's (DOE) energy conservation standards (10 CFR 431.196). You must provide a compliance certification to U.S. Customs and Border Protection (CBP) upon entry, confirming the model meets the mandated minimum efficiency levels.
For HTS 850431 small power transformers, how does the core material (e.g., ferrite vs. laminated iron) affect the classification or duty rate?
The core material does not affect classification under HTS 850431, as the heading is defined by power handling capacity (≤1 kVA). However, the specific material composition can influence the assessment of anti-dumping or countervailing duties, as certain transformer cores made of non-grain oriented electrical steel from specific countries may be subject to additional tariffs.
Similar and Commonly Confused HTS Codes
Small power transformers under 8504.31 are most often confused with larger power transformers (8504.23 or 8504.33, depending on rating) and with parts of transformers (8504.90). For electronic applications, it is critical to distinguish them from signal or pulse transformers, which are generally classified in heading 8504.50. Additionally, ensure the device is not merely an inductor or coil, which would fall under 8504.50. Proper classification depends on the primary function of transforming AC voltage, a power handling capacity typically under 1 kVA for this subheading, and exclusion from being a part.
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