8421.21.00.00—For filtering or purifying water
General
Free
Units
No.
Column 2
35%
Special
—
8421.21.00.00—For filtering or purifying waterGeneral
Free
Units
No.
Column 2
35%
Special
—
HTS 8421.21.00.00 is the U.S. Harmonized Tariff Schedule classification for For filtering or purifying water. It's a 10-digit statistical line in Chapter 84: Nuclear reactors, boilers, machinery and mechanical appliances; parts thereof, Section XVI: Machinery and Mechanical Appliances; Electrical Equipment; Parts Thereof; Sound Recorders and Reproducers, Television Image and Sound Recorders and Reproducers, and Parts and Accessories of Such Articles, used by U.S. Customs and Border Protection to determine the duty rate at entry. 5 Chapter 99 tariff modifications currently stack on top of the base rate.
New to HTS codes? Read our guide on how HTS classification works →
Chapter 99 overlays that stack on the base rate
| Code | Authority | Rate |
|---|---|---|
| 9903.74.08 | section_232 | The duty provided in the applicable subheading + 25% |
| 9903.74.09 | section_232 | The duty provided in the applicable subheading + 25% |
| 9903.74.10 | section_232 | The duty provided in the applicable subheading |
| 9903.74.11 | section_232 | The duty provided in the applicable subheading |
| 9903.88.69 | section_301 | The duty provided in the applicable subheading |
Past CBP decisions classifying real products under this HTS code. Useful precedent when classifying a similar product — each ruling shows how CBP interpreted the code for a specific case.
The tariff classification of a robotic pool skimmer from China
The tariff classification, country of origin, and eligibility of the United States-Mexico-Canada Agreement of an Electrochemical Water Purification System
The tariff classification and country of origin of a water filtration device
The tariff classification of an aquarium gravel cleaner from China
The tariff classification of water filter components from the United Kingdom
Source: CBP CROSS (view all rulings on rulings.cbp.gov →)
HTS 8421.21.00.00 is the U.S. Harmonized Tariff Schedule classification for For filtering or purifying water. It belongs to Chapter 84 of the HTSUS.
The general (Column 1) duty rate for HTS 8421.21.00.00 is Free. This is the most-favored-nation (MFN) rate that applies to imports from World Trade Organization member countries.
The Column 2 rate for HTS 8421.21.00.00 is 35%. This rate applies to imports from countries that do not have normal trade relations with the United States (currently Cuba and North Korea).
Yes — HTS 8421.21.00.00 is covered by section_232 provision 9903.74.08 (The duty provided in the applicable subheading + 25%). 4 additional overlays also touch this code. Open the code page for the full overlay stack with effective dates and country scopes.
No active AD/CVD orders currently flag HTS 8421.21.00.00 in Tandom's catalog. Tandom monitors Federal Register notices daily; a flag will appear here within 24h of any new order's publication.
Tandom guides relevant to this code
What the 178 active Section 301 exclusions cover, how to claim 9903.88.69 on an entry, and what changes when the November 10, 2026 deadline passes.
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How to read, order, and report Chapter 99 HTS codes alongside the base classification on a US entry summary in 2026. The full stacking ladder for brokers and compliance teams.
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A working guide to the inputs, the layers, and the math behind a US entry summary in 2026. Written for brokers, forwarders, and importer compliance teams.
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What changed April 6, 2026, what stayed the same, and how to file a steel, aluminum, or copper line in ACE without leaving duty exposure on the table.
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Drop the Tandom Duty Calculator API into a TMS, broker software, or in-house ERP. Code samples, the response shape, and ACE reporting order, in 2026.
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Where trade compliance APIs fit in a broker's filing pipeline: HTS classification, duty calculation, AD/CVD scope match, and post-summary corrections.
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