These additions will generally take effect for tax purposes starting 1 January 2026, while the specific effective dates for refund claims under section 4662(e) are detailed individually for each substance.

The US Treasury Department and Internal Revenue Service (IRS), in a notice, announced that 39 new substances will be added to the list of chemicals subject to the excise tax under section 4671(a), following requests submitted under Rev. Proc. 2022-26.

These additions will generally take effect for tax purposes starting 1 January 2026, while the specific effective dates for refund claims under section 4662(e) are detailed individually for each substance.

This notice of determinations modifies the list of taxable substances to include the following 39 substances:

  1. Acrylonitrile-butadiene rubber
  2. Bromo-isobutene-isoprene rubber
  3. Chloroprene rubber
  4. Ethylene-propylene-ethylidene norbornene rubber
  5. Ethylene vinyl acetate
  6. Ethylene vinyl acetate
  7. Hydrogenated acrylonitrile-butadiene rubber
  8. Isobutene-isoprene rubber
  9. Poly(ethylene-propylene) rubber
  10. Emulsion styrene-butadiene rubber
  11. Solution styrene-butadiene rubber
  12. Emulsion styrene butadiene rubber
  13. Solution styrenebutadiene rubber
  14. Hydrogenated acrylonitrilebutadiene rubber
  15. Bromobutyl isobutylene isoprene rubber
  16. Chlorobutyl isobutylene isoprene rubber
  17. DIPE–di-isopropyl ether
  18. Di-isodecyl phthalate
  19. Di-isononyl adipate
  20. Di-isononyl phthalate
  21. Di-tridecyl phthalate
  22. Ethylene propylene diene (EPDM) rubber
  23. Isodecyl alcohol
  24. Isodecyl benzoate
  25. Isooctyl alcohol
  26. Linear nonyl phthalate
  27. Linear nonyl undecyl phthalate
  28. Linear undecyl phthalate
  29. Linear nonyl tri-mellitate
  30. Neo decanoic acid
  31. Neo pentanoic acid
  32. Nonene
  33. Regular butyl rubber
  34. Tridecyl alcohol
  35. Tri-isononyl trimellitate
  36. Di-isobutylene
  37. Polyisobutylene
  38. Styrene-acrylonitrile
  39. Acrylonitrile butadiene styrene