BIS September 24, 2026 Rule Removes the Section 232 Aluminum and Steel Derivatives Inclusions Process: What Machined-Component Buyers Should Re-Verify

Last verified: October 9, 2026. This article reflects the Federal Register documents and dates cited below, checked on that date.

What Happened, and Why Metal Buyers Should Notice

On September 22, 2026, the U.S. Bureau of Industry and Security (BIS) issued a temporary final rule titled “Measures To Restrict Stockpiling of Polysilicon and Polysilicon Derivatives Under Proclamation 11052.” The rule was published in the Federal Register on September 24, 2026. Its headline subject is polysilicon, the base material for semiconductors and solar products.

But buried in the “Regulatory Changes” section of the same document is a change that matters much more directly to anyone buying or specifying machined metal components: the rule removes the aluminum and steel derivatives inclusions process from Supplement No. 1 to 15 CFR Part 705.

According to the rule’s own text, this removal is done “consistent with Proclamation 11021 of April 2, 2026,” which had already terminated the aluminum, steel, and copper derivatives inclusions process established in Proclamations 10895 and 10896 (February 10, 2025) and Proclamation 10962 (July 30, 2025). In plain terms, the September 24 rule clears the old inclusions framework out of the Code of Federal Regulations.

The Facts as Documented

The following points are drawn directly from the two primary sources cited at the end of this article:

• Document and date: BIS temporary final rule, Docket No. 260915-0004, RIN 0694-AK57, published in the Federal Register (Vol. 91, No. 184, pages 60505–60510) on September 24, 2026. It is effective from September 22, 2026 through December 3, 2026 (Federal Register, 2026-19537).
• Predecessor proclamation: Proclamation 11052, “Adjusting Imports of Polysilicon and Its Derivatives Into the United States,” was issued August 6, 2026. It imposed minimum import prices and tariffs on polysilicon and polysilicon derivatives under Section 232 of the Trade Expansion Act of 1962, with those import adjustments taking effect December 4, 2026.
• Stockpiling restriction: The rule restricts existing importers of record that BIS determines are importing polysilicon products “in volumes substantially greater than their historic averages.” New importers of record registered on or after August 6, 2026 face weekly quantity limits unless they obtain a waiver.
• The metal-relevant change: The same rule states that “this TFR also removes the aluminum and steel inclusions process.” Before this rule, Supplement No. 1 to Part 705 had “established the regulatory framework for the inclusions process for aluminum and steel duties implemented by the President.”

One important clarification for accuracy: the change means that companies can no longer rely on the old Section 232 derivatives inclusions process for aluminum and steel. The underlying Section 232 tariffs on aluminum, steel, and copper and their derivative products were already being reshaped by Proclamation 11021 (April 2, 2026) and later actions; the September 24 rule removes the procedural mechanism, not the tariffs themselves.

Why This Connects to Precision Manufacturing

Buyers of CNC-machined metal parts rarely buy polysilicon. So why read a rule about it? Because of what the rule does to the tariff architecture that machined-component buyers depend on.

The Section 232 aluminum and steel derivatives inclusions process was the formal channel through which importers could request that specific derivative articles be included within — or excluded from — the scope of the metal tariffs. For a machine shop, a distributor, or an OEM sourcing aluminum or stainless parts, that process shaped several practical questions: whether a given imported part carried the metal tariff at all, how the metal content was declared, and what documentation a supplier needed to provide.

When that process is removed, the basis for many scope expectations becomes less certain, even though the tariffs continue. Precision-manufacturing buyers who built sourcing and costing models around specific inclusion or exclusion outcomes should treat those assumptions as needing re-verification rather than as settled.

Impact on Materials, Processes, Lead Times, Cost, and Compliance

Materials. The removal applies to the aluminum and steel derivatives framework. Copper is referenced in the same regulatory chain (Proclamations 10962 and 11021), and the 2026 Unified Agenda indicates BIS has planned a separate copper tariffs inclusions process. Buyers of aluminum, stainless steel, copper, and brass components should watch each material line individually rather than assuming a single blanket rule.

Processes. The change is procedural, not a machining-method change. It does not alter cutting parameters, tooling, or tolerances. What it can alter is the paperwork and landed-cost logic that surrounds a finished machined part.

Lead times. Scope clarifications that previously came through the inclusions path may now need to be resolved through other channels — Section 232 derivative scope notices, customs rulings, or the filings cited in Proclamation 11021. Uncertainty in scope can translate into customs holds or delayed clearance, which affects delivery schedules even when production runs normally.

Cost. Landed cost depends on whether a given imported machined part is treated as a covered metal derivative. If prior exclusions or inclusions are no longer available through the old process, effective duty exposure for some parts can change. This is a documented procedural change, not a forecast of a specific price move; the direction of any cost impact depends on the specific part and HTSUS classification.

Compliance. Importers of record should confirm which mechanism, if any, now governs their products. The September 24 rule emphasizes importer-of-record obligations, waiver documentation, and customs-broker diligence in the polysilicon context — a reminder that metal-derivative scope claims generally require accurate documentation and cannot be assumed.

What Buyers Should Verify

These are practical, checkable actions rather than predictions:

• Identify your HTSUS classification for each imported aluminum, steel, and copper part, and confirm whether it was ever covered by an inclusion or exclusion under the old Part 705 process.
• Ask suppliers to state their current tariff treatment in writing, and ask whether their position rested on the now-removed inclusions process.
• Re-check the derivative scope notices. Commerce has been actively adjusting derivative article lists; the August 6, 2026 request for comments proposed adding 14 additional derivative articles, and that process runs on its own track.
• Confirm importer-of-record and broker responsibilities for any product whose scope may be ambiguous.
• Document the basis of each scope and duty assumption, so a future scope change can be traced rather than relitigated from memory.

Related background already covered on this site includes the Proclamation 10984 tariff-relief procedures notice and its primary-metal focus, the proposal to add 14 derivative articles to Section 232 steel, aluminum, and copper duties, and the partial revocation of aluminum sheet duties for can stock. Buyers sourcing aluminum workpieces may also find the material overviews under the site’s aluminum alloys category useful for specification comparisons.

A Limited Conclusion

What is confirmed: BIS published a temporary final rule on September 24, 2026 that restricts polysilicon stockpiling and, in the same document, removes the aluminum and steel derivatives inclusions process from the Section 232 regulatory framework. The rule is effective September 22 through December 3, 2026.

What is a third-party plan, not a completed action: BIS’s 2026 Unified Agenda lists a planned copper tariffs inclusions process; a listing in the Unified Agenda is a statement of intent, not a finished rule.

What is the author’s analysis, clearly labeled as such: the practical significance for machined-component buyers is that a familiar procedural path for clarifying metal-tariff scope has been removed, which raises the value of verifying HTSUS classifications and supplier documentation now rather than assuming prior outcomes still hold. This article does not predict specific price or lead-time changes, because those depend on part-specific facts.

Buyers should verify their own classifications and supplier positions against the primary documents below before making sourcing or costing decisions.

Sources

• BIS temporary final rule, “Measures To Restrict Stockpiling of Polysilicon and Polysilicon Derivatives Under Proclamation 11052,” Federal Register Vol. 91, No. 184, published September 24, 2026 (effective September 22–December 3, 2026): federalregister.gov/documents/2026/09/24/2026-19537
• Commerce/BIS notice, “Request for Public Comments on the Proposed Implementation of Duties on Additional Aluminum, Steel, and Copper Derivative Articles Under Section 232,” published August 6, 2026 (comments closed August 27, 2026): federalregister.gov/documents/2026/08/06/2026-15961
• Presidential Proclamation 11021, “Strengthening Actions Taken to Adjust Imports of Aluminum, Steel, and Copper Into the United States,” April 2, 2026 (91 FR 18201), as referenced in the September 24, 2026 rule.

Sources retrieved October 9, 2026. This article summarizes official documents and does not provide legal or customs advice; importers should consult a licensed customs broker or trade counsel for classifications specific to their products.