# HTS 3913: Natural polymers (for example, alginic acid) and modified natural polymers (for example, hardened proteins, chemical derivatives of natural rubber), not elsewhere specified or included, in primary forms:

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Source: [2026 HTS Revision 21 (October 9, 2026)](https://hts.usitc.gov/search?query=3913). Additional duties by country of origin may apply; estimate a shipment's full duty with the tariff calculator: https://geopax.app/tariffs/calculator

## 3913: Natural polymers (for example, alginic acid) and modified natural polymers (for example, hardened proteins, chemical derivatives of natural rubber), not elsewhere specified or included, in primary forms:

| Code | Description | General | Special | Column 2 | Units |
| --- | --- | --- | --- | --- | --- |
| 3913 | Natural polymers (for example, alginic acid) and modified natural polymers (for example, hardened proteins, chemical derivatives of natural rubber), not elsewhere specified or included, in primary forms: |  |  |  |  |
| 3913.10.00.00 |   Alginic acid, its salts and esters | 4.2% | Free (A,AU,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG) | 25% | kg |
| 3913.90 |   Other: |  |  |  |  |
| 3913.90.10.00 |     Chemical derivatives of natural rubber | Free |  | 20% | kg |
| 3913.90.20 |     Polysaccharides and their derivatives | 5.8% | Free (A*,AU,BH,CL,CO,D,E,IL,JO,K,KR,MA,OM,P,PA,PE,S,SG) | 50% |  |
| 3913.90.20.15 |       Xanthan gum | 5.8% | Free (A*,AU,BH,CL,CO,D,E,IL,JO,K,KR,MA,OM,P,PA,PE,S,SG) | 50% | kg |
| 3913.90.20.90 |       Other | 5.8% | Free (A*,AU,BH,CL,CO,D,E,IL,JO,K,KR,MA,OM,P,PA,PE,S,SG) | 50% | kg |
| 3913.90.50.00 |     Other | 6.5% | Free (A*,AU,BH,CL,CO,D,E,IL,JO,K,KR,MA,OM,P,PA,PE,S,SG) | 2.2¢/kg + 33.5% | kg |