# HS code 2835.31: Polyphosphates, sodium triphosphate (sodium tripolyphosphate)

> HS code 2835.31 covers polyphosphates, sodium triphosphate (sodium tripolyphosphate). It sits in heading 28.35 (phosphinates (hypophosphites), phosphonates (phosphites) and phosphates; polyphosphates, whether or not chemically defined) in chapter 28 (inorganic chemicals; organic or inorganic compounds of precious metals, of rare-earth metals, of radioactive elements or of isotopes). Other goods of heading 28.35 are classified under 2835.10 (phosphinates (hypophosphites) and phosphonates (phosphites)), 2835.22 (phosphates, of mono- or disodium), 2835.24 (phosphates, of potassium), 2835.25 (phosphates, calcium hydrogenorthophosphate (“dicalcium phosphate”)) or 3 others. National tariff lines under 2835.31 are live on border.bot for the United States (1 line, also used by 1 other country).

Source: https://border.bot/hs-codes/283531
Last updated: 11 October 2026

[HS codes](https://border.bot/hs-codes) / [Chapter 28](https://border.bot/hs-codes/28) / [28.35](https://border.bot/hs-codes/2835) / [2835.31](https://border.bot/hs-codes/283531)

## Key facts

- HS code: 2835.31
- Covers: Polyphosphates, sodium triphosphate (sodium tripolyphosphate)
- Heading: [28.35: Phosphinates (hypophosphites), phosphonates (phosphites) and phosphates; polyphosphates, whether or not chemically defined](https://border.bot/hs-codes/2835)
- Chapter: [28: Inorganic chemicals; organic or inorganic compounds of precious metals, of rare-earth metals, of radioactive elements or of isotopes](https://border.bot/hs-codes/28)
- Edition: HS2022
- Duty in the United States: [See its 1 line](https://border.bot/countries/united-states/hs-codes/283531)

## What this code covers

HS code 2835.31 covers polyphosphates, sodium triphosphate (sodium tripolyphosphate).

The legal text of the subheading is “Polyphosphates: Sodium triphosphate (sodium tripolyphosphate)”, read under “Polyphosphates”, in HS2022.

## What it doesn’t cover

Other goods of heading 28.35 are classified under 2835.10 (phosphinates (hypophosphites) and phosphonates (phosphites)), 2835.22 (phosphates, of mono- or disodium), 2835.24 (phosphates, of potassium), 2835.25 (phosphates, calcium hydrogenorthophosphate (“dicalcium phosphate”)) or 3 others.

- [2835.10](https://border.bot/hs-codes/283510) Phosphinates (hypophosphites) and phosphonates (phosphites)
- [2835.22](https://border.bot/hs-codes/283522) Phosphates: Of mono- or disodium
- [2835.24](https://border.bot/hs-codes/283524) Phosphates: Of potassium
- [2835.25](https://border.bot/hs-codes/283525) Phosphates: Calcium hydrogenorthophosphate (“dicalcium phosphate”)
- [2835.26](https://border.bot/hs-codes/283526) Phosphates: Other phosphates of calcium
- [2835.29](https://border.bot/hs-codes/283529) Phosphates: Other
- [2835.39](https://border.bot/hs-codes/283539) Polyphosphates: Other

## How it is structured

2835.31 is a six-digit subheading. Its first two digits, 28, are the chapter; the first four, 2835, are heading 28.35; the last two, 31, identify the subheading within the heading.

Countries add their own digits after these six for their national tariff lines.

- Chapter 28: Inorganic chemicals; organic or inorganic compounds of precious metals, of rare-earth metals, of radioactive elements or of isotopes
- Heading 28.35: Phosphinates (hypophosphites), phosphonates (phosphites) and phosphates; polyphosphates, whether or not chemically defined
- Within the heading: Polyphosphates
- Subheading 2835.31: Sodium triphosphate (sodium tripolyphosphate)

## In other countries

National tariff lines under 2835.31 are live on border.bot for the United States (1 line, also used by 1 other country).

- [United States](https://border.bot/countries/united-states/hs-codes/283531): 1 line, used by 1 other country

- Previous subheading: [2835.29](https://border.bot/hs-codes/283529) Phosphates: Other
- Next subheading: [2835.39](https://border.bot/hs-codes/283539) Polyphosphates: Other

## Frequently asked questions

### What does HS code 2835.31 cover?

HS code 2835.31 covers polyphosphates, sodium triphosphate (sodium tripolyphosphate).

### Which heading and chapter is HS code 2835.31 in?

HS code 2835.31 is in heading 28.35 (phosphinates (hypophosphites), phosphonates (phosphites) and phosphates; polyphosphates, whether or not chemically defined) in chapter 28 (inorganic chemicals; organic or inorganic compounds of precious metals, of rare-earth metals, of radioactive elements or of isotopes).

### Where are goods of heading 28.35 classified when 2835.31 doesn’t fit?

Other goods of heading 28.35 are classified under 2835.10 (phosphinates (hypophosphites) and phosphonates (phosphites)), 2835.22 (phosphates, of mono- or disodium), 2835.24 (phosphates, of potassium), 2835.25 (phosphates, calcium hydrogenorthophosphate (“dicalcium phosphate”)) or 3 others.

### Which countries’ tariffs list national lines under HS code 2835.31?

National tariff lines under 2835.31 are live on border.bot for the United States (1 line, also used by 1 other country).

## Sources and updates

The Harmonized System legal text comes from border.bot release 2 (edition HS 2022), imported from a file, and has been live since 11 October 2026.

This page was last updated on 11 October 2026.

Guidance from published tariff data, not a binding ruling. For a decision customs must follow, apply to the destination’s customs authority for a binding tariff ruling.

Machine-readable: https://border.bot/hs-codes/283531.json