Superfund Chemical Excise Tax Explained
Despite the single name, the Superfund chemical excise tax is two separate taxes. One applies when a manufacturer, producer, or importer sells or uses a taxable chemical. The other applies when an importer sells or uses a finished substance made from those chemicals. Both came back on July 1, 2022, after expiring on December 31, 1995. If your business makes or brings in chemicals, polymers, or similar materials, here's how to tell whether you're in scope. Our Superfund chemical tax filing page covers the return side.
The two taxes, and a third Superfund tax on oil
| Taxable chemicals | Imported substances | Petroleum | |
|---|---|---|---|
| Code section | 4661 | 4671 | 4611 |
| IRS No. on Form 720 | 54 | 17 | 53 (domestic), 16 (imported) |
| Who is liable | Manufacturer, producer, or importer who sells or uses it | Importer who sells or uses it | Refinery operator, user, or person entering the product |
| Unit | Per ton | Per ton, or 10% of entry value | $0.18 per barrel in 2026 |
The petroleum rate is a separate tax that happens to share the Superfund label, formally the Hazardous Substance Superfund financing rate. This guide stays on the two chemical taxes.
Taxable chemicals and IRS No. 54
A taxable chemical is any substance listed in the table under section 4661(b) that is made in the United States or entered for consumption, use, or warehousing. The list and per-ton rates are on Form 6627, Part II. We don't reproduce them here, since the form is the place to read them for your return period.
Importing can put you on both tracks. A company that brings in a listed chemical is an importer of a taxable chemical under IRS No. 54. A company that brings in a downstream product on the substance list is under IRS No. 17.
How are imported chemical substances taxed?
The logic of IRS No. 17 is equal treatment. The tax equals what the chemical tax would have been on the taxable chemicals used to make the substance, if it had been made here. The instructions carry a long Table of Taxable Imported Chemical Substances. Here's a sample showing the range and the effective dates:
| Substance | Rate per ton | Effective date |
|---|---|---|
| Acetone | $20.06 | July 1, 2022 |
| Styrene | $9.93 | July 1, 2022 |
| Polypropylene | $9.74 | July 1, 2022 |
| Polyoxymethylene | $3.65 | October 1, 2024 |
| Nylon 6 | $14.77 | January 1, 2026 |
| Potassium carbonate | $0.36 | January 1, 2026 |
| Ethyl acetate | Not yet shown (*) | July 1, 2022 |
The January 2026 update added 60 substances, so a material that wasn't taxable in 2025 may be now. Check the table each year rather than relying on last year's review. The IRS also posts updates at IRS.gov/Form6627 and answers common questions at IRS.gov/scetfaqs.
Three ways to figure the imported substance tax
- Conversion factor. The ratio of the weight of each taxable chemical used to the total weight of the substance. For each chemical, multiply tons by the factor and by that chemical's Part II rate.
- IRS-provided rate. If you lack the information for a factor and the IRS has a rate, multiply tons by the rate.
- 10% of value. If you lack the information and the IRS hasn't provided a rate, the tax is 10% of the substance's appraised entry value.
Two examples, with an invented company and invented quantities:
| Import | Method | Math | Tax |
|---|---|---|---|
| 200 tons of styrene sold | IRS rate | 200 x $9.93 | $1,986.00 |
| Ethyl acetate with $80,000 appraised entry value, composition unknown, no IRS rate shown | 10% of value | $80,000 x 10% | $8,000.00 |
Keep your supplier's composition data if you can get it. The 10% route is based on value rather than tons, so the result can differ a lot from the per-ton routes, and the instructions leave room to calculate your own rate whether or not the IRS has provided one.
How the tax reaches Form 720
Pub. 510 puts it in one line: figure the environmental tax on Form 6627, enter it on the appropriate lines of Form 720, and attach Form 6627. In practice:
- Enter chemicals on IRS No. 54 and imported substances on IRS No. 17, under "Environmental Taxes" in Form 720, Part I.
- Complete Schedule A, because it's required when you have an entry in Part I.
- Make semimonthly deposits as generally required, unless net Part I liability doesn't exceed $2,500 for the quarter. Then the tax is payable with the return.
- File by the quarterly date. The fourth quarter 2026 return is due Monday, February 1, 2027, since January 31 is a Sunday.
No one is exempt on the basis of who they are. Pub. 510 says that includes the federal government, state and local governments, Indian tribal governments, and nonprofit educational organizations. Claims for credit do exist. Schedule C uses CRN 454 for chemicals and CRN 317 for imported substances, and claims generally must be filed within 3 years from when the return was filed or 2 years from when the tax was paid, whichever is later. Section 4662(e) refund claims for a newly added substance have their own effective dates, set out in the notices the instructions cite.
Reporting Nos. 54 and 17 online
Once your tons and any entry values are worked out on Form 6627, you can file Form 720 online with EasyFile720, an IRS-authorized e-file provider covering Part I categories and Schedules A and C. You enter your figures, the math is calculated, and validations catch common mistakes before you submit. An account is free to start, and you pay $39.95 per filing. A quarterly filer may prefer the Full Year Plan at $139.99 for 4 filing credits, as shown on the pricing page. For more on this line, see our Superfund chemical tax page, or check who must file Form 720 if this would be your first return.
FAQ
I buy chemicals from a U.S. supplier. Do I owe this tax?▼
The tax is imposed on the sale or use of taxable chemicals by manufacturers, producers, and importers of those chemicals. A buyer that is none of those is not the party the IRS sources name as liable.
What does an asterisk in the IRS substance table mean?▼
It means the rate per ton may be determined later. The IRS publishes those rates at IRS.gov/Form6627 when they become available.
Does this apply in Puerto Rico or a foreign trade zone?▼
For environmental tax purposes, Pub. 510 defines the United States to include the Commonwealth of Puerto Rico, U.S. territories, the continental shelf areas, and foreign trade zones, among others.
Can a substance be added to or removed from the list?▼
Yes. Rev. Proc. 2022-26 gives the procedure for requesting that determination, and the IRS adds substances over time, including 60 effective January 1, 2026.
File Form 720 online
Create a free account with no credit card and build your return. You pay $39.95 only when you file. EasyFile720 is an IRS-authorized e-file provider, and you get an acknowledgment when the IRS accepts your return.
Sources: Instructions for Form 6627 (Rev. January 2026); Pub. 510 (Rev. December 2025); Instructions for Form 720 (Rev. June 2026); Form 720 (Rev. June 2026); IRS Form 720 Business Rules Publication 2026Q4 v1.0. General information, not tax advice. Confirm how the rules apply to you with a qualified advisor or the IRS.
