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

Every line of heading 3913

• 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 (kg): General 4.2%; Special Free (A,AU,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG); Column 2 25%.
• 3913.90 Other (under: 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).
• 3913.90.10.00 Chemical derivatives of natural rubber (kg): General Free; Special none; Column 2 20%.
• 3913.90.20 Polysaccharides and their derivatives: General 5.8%; Special Free (A*,AU,BH,CL,CO,D,E,IL,JO,K,KR,MA,OM,P,PA,PE,S,SG); Column 2 50%.
• 3913.90.20.15 Xanthan gum (under: Polysaccharides and their derivatives) (kg).
• 3913.90.20.90 Other (under: Polysaccharides and their derivatives) (kg).
• 3913.90.50.00 Other (under: Other) (kg): General 6.5%; Special Free (A*,AU,BH,CL,CO,D,E,IL,JO,K,KR,MA,OM,P,PA,PE,S,SG); Column 2 2.2¢/kg + 33.5%.

About these rates

The rates are those printed in the 2026 HTS Revision 23, published by the U.S. International Trade Commission. A 10-digit statistical line takes the rates printed on the 8-digit line above it. Chapter 99 duties (Section 232, Section 301, IEEPA) depend on the product, the origin and the date, are charged on top, and are not included. A code here is a strong lead, not a ruling: confirm it with a customs broker or a CBP binding ruling.