HSN code 39031100 is the 8-digit tariff item for expansible, under heading 3903 and sub-heading 390311 (Chapter 39). GST is 18%: 9% CGST + 9% SGST within a state, or 18% IGST to another state. Rates as of 2026-10-21.
HSN 39031100 at a glance
| Tariff item (8 digits) | 39031100 |
|---|---|
| Heading (4 digits) | 3903: Polymers of styrene, in primary forms |
| Sub-heading (6 digits) | 390311: Expansible |
| Chapter | 39: Plastics and articles thereof |
| Description | Expansible |
| GST rate | 18% |
| Within the state | 9% CGST + 9% SGST (or UTGST) |
| To another state | 18% IGST |
9/2025-CT(R), Schedule II, S. No. 114 (HSN 3901 to 3913) covers "All goods i.e. polymers; Polyacetals, other polyethers, epoxide resins, polycarbonates, alkyd resins, polyallyl esters, other polyesters; polyamides..." at 18%. Goods of this code outside that wording fall under the 18% residual entry, so the rate is 18% either way.
The rate entry for this code
The description is the notification's own wording. An entry applies only when the goods match it.
| HSN scope | Description of goods | GST | CGST + SGST | Entry |
|---|---|---|---|---|
| 3901 to 3913 | All goods i.e. polymers; Polyacetals, other polyethers, epoxide resins, polycarbonates, alkyd resins, polyallyl esters, other polyesters; polyamides; Amino-resins, phenolic resins and polyurethanes; silicones; Petroleum resins, coumarone-indene resins, polyterpenes, polysulphides, polysulphones and other products specified in Note 3 to this Chapter, not elsewhere specified or included; Cellulose and its chemical derivatives, not elsewhere specified or included; 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 | 18% | 9% + 9% | 9/2025-CT(R), Schedule II, S. No. 114 |
| Any | Goods which are not specified in Schedule I, III, IV, V, VI or VII (residual entry, for goods of 39031100 that match none of the descriptions above) | 18% | 9% + 9% | 9/2025-CT(R), Schedule II, S. No. 639 |
Worked example: a ₹1,000 sale under HSN 39031100
Taxable value ₹1,000.00. Within your state: CGST ₹90.00 + SGST ₹90.00 = ₹180.00, invoice total ₹1,180.00. To a buyer in another state: IGST ₹180.00, the same total.
For other amounts, or to work back from a tax-inclusive price, use the GST calculator.
How many HSN digits to print on the invoice
Notification 78/2020-Central Tax sets the minimum by aggregate turnover in the previous financial year: up to ₹5 crore, at least 4 digits (3903) on tax invoices to registered buyers (optional on B2C invoices); above ₹5 crore, at least 6 digits (390311) on all tax invoices. Exports and imports are declared on the shipping bill or bill of entry under the full 8-digit tariff item (39031100), so most exporters print 8 digits on their GST invoices too.
The HSN-wise summary in GSTR-1 uses the same code, so set it once on the item in your billing software. FundRaksha Book stores the HSN and GST rate on each item, splits CGST, SGST and IGST on every bill, and keeps stock and party ledgers alongside.
Other tariff items under heading 3903
- HSN 39031910: Polymers of styrene, in primary forms, other, moulding powder (18%)
- HSN 39032000: Styrene-acrylonitrile (san) copolymers (18%)
- HSN 39033000: Acrylonitrile-butadine-styrene (ABS) copolymers (18%)
- HSN 39039010: Copolymers, solely of styrene with allyl alcohol, of any acetyl value of 175 or more (18%)
- HSN 39039020: Brominated polystyrene, containing by weight 58% or more but not more than 71% of bromine, in one of the... (18%)
See every rate entry for the heading on the HSN 3903 page, or all Chapter 39 headings.
Sources
Codes and descriptions: GSTN HSN master (HSN_SAC.xlsx, sheet HSN_MSTR), GST portal, file dated 13.10.2026, read on 21.10.2026; descriptions were converted from capitals and joined with their heading and sub-heading text. Rates: Rates from Notification 9/2025-Central Tax (Rate), 17.09.2025, as amended by Notification 19/2025-Central Tax (Rate) (from 01.02.2026) and Notification 01/2026-Central Tax (Rate) (from 01.05.2026); nil-rated goods from Notification 10/2025-Central Tax (Rate); bricks from Notification 14/2025-Central Tax (Rate).