As part of the ongoing implementation of the reinstated Superfund Excise Tax, the IRS has issued a notice of determination modifying the current list of taxable substances under IRC § 4671 (excise taxes on related substances sold or used by importers). This update reflects the addition of 39 new chemical substances that will be subject to the Superfund Excise Tax.
What’s Superfund Excise Tax:
The Superfund tax is a federal excise tax designed to fund the cleanup of hazardous waste sites through the Hazardous Substance Superfund. Its purpose is to ensure that manufacturers, producers, and importers of certain chemicals and chemical derivatives contribute to the costs of remediating environmental contamination.
These newly added substances are used in a broad range of industries. Taxpayers importing or using these substances in the U.S. will be required to comply with federal excise tax requirements starting January 1, 2026.
The 39 substances added to the taxable substances list under IRC § 4672(a)(2) include the following:
| Chemical Substances | Rate/Ton ($) |
| Acrylonitrile-butadiene rubber | 9.58 |
| Bromo-isobutene-isoprene rubber | 9.72 |
| Chloroprene rubber | 10.51 |
| Ethylene-propylene-ethylidene norbornene rubber | 9.25 |
| Ethylene vinyl acetate (VA < 50%) | 7.09 |
| Ethylene vinyl acetate (VA ≥ 50%) | 6.77 |
| Hydrogenated acrylonitrile-butadiene rubber | 9.54 |
| Isobutene-isoprene rubber | 9.64 |
| Poly(ethylene-propylene) rubber | 9.74 |
| Emulsion styrene-butadiene rubber | 9.74 |
| Solution styrene-butadiene rubber | 9.74 |
| Emulsion styrene-butadiene rubber (variant) | 9.74 |
| Solution styrene-butadiene rubber (variant) | 9.74 |
| Hydrogenated acrylonitrile-butadiene rubber (high-molecular formula) | 10.02 |
| Bromobutyl isobutylene isoprene rubber | 9.63 |
| Chlorobutyl isobutylene isoprene rubber | 9.50 |
| Di-isopropyl ether (DIPE) | 7.99 |
| Di-isodecyl phthalate | 7.31 |
| Di-isononyl adipate | 7.07 |
| Di-isononyl phthalate | 7.11 |
| Di-tridecyl phthalate | 7.50 |
| Ethylene propylene diene (EPDM) rubber | 9.45 |
| Isodecyl alcohol | 7.01 |
| Isodecyl benzoate | 7.60 |
| Isooctyl alcohol | 6.62 |
| Linear nonyl phthalate | 7.69 |
| Linear nonyl undecyl phthalate | 7.89 |
| Linear undecyl phthalate | 7.89 |
| Linear nonyl tri-mellitate | 5.55 |
| Neo decanoic acid | 6.43 |
| Neo pentanoic acid | 5.36 |
| Nonene | 8.77 |
| Regular butyl rubber | 9.64 |
| Tridecyl alcohol | 7.40 |
| Tri-isononyl tri-mellitate | 5.06 |
| Di-isobutylene | 9.74 |
| Polyisobutylene | 9.74 |
| Styrene-acrylonitrile | 9.91 |
| Acrylonitrile butadiene styrene (ABS) | 9.90 |
For more detailed information, please visit the IRS website, Internal Revenue Bulletin: 2025-41.
Effective Date
The effective date for these newly added substances is January 1, 2026. Starting on this date, importers or users of these substances must begin reporting and paying the applicable excise taxes under IRC § 4671.
Our team is prepared to assist you with:
- Calculating the federal excise tax liability.
- Assisting with filing the federal excise tax returns and semi-monthly deposit reporting.
- Assist with all compliance obligations, including filing returns on Forms 720 and Form 6627
For additional information or assistance with compliance planning ahead of the January 1, 2026 effective date, please contact our team.
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