Did You Overpay Section 301 Duties on Chinese-Made Pump Parts or Plastic Components? A New CBP Refund Window Just Opened

If your company imports pumps, compressors, or certain plastic components from China, there's a narrow but real chance you overpaid Section 301 duties over the past three months — and U.S. Customs and Border Protection just opened the door to get that money back.

On September 22, 2026, CBP released CSMS #69990649, providing entry-filing instructions tied to a Section 301 exclusion update that most importers never saw coming because it started as a routine statistical housekeeping notice.

What Happened

Back on July 1, 2026, the U.S. International Trade Commission made routine changes to several 10-digit statistical reporting categories in the Harmonized Tariff Schedule of the United States (HTSUS) — the kind of numbering cleanup that happens periodically and rarely makes headlines. The problem: four Section 301 China exclusions on the books referenced the old HTS numbers. Once those numbers changed, the exclusions technically no longer lined up with the correct classification codes, putting importers of the covered goods at risk of losing exclusion coverage without any public notice.

The Office of the U.S. Trade Representative fixed the mismatch in a Federal Register notice published September 2, 2026, making conforming amendments to U.S. notes 20(vvv)(i)(4), 20(vvv)(i)(5), 20(vvv)(i)(6), and 20(vvv)(iv)(4) to subchapter III of chapter 99 of the HTSUS, filed under exclusion umbrella HTSUS 9903.88.69. Critically, USTR made the fix effective retroactively to July 1, 2026 — the date the underlying HTS numbers changed — so there's no coverage gap.

The affected exclusions now describe statistical reporting numbers 8413.91.9039, 8413.91.9046, 8413.91.9059, and 8413.91.9099 (pump, compressor, and fan parts) and 3926.90.9915 and 3926.90.9920 (other plastic articles). Before July 1, these same goods were reported under 8413.91.9065, 8413.91.9085, 8413.91.9096, and 3926.90.9910. CBP's September 22 CSMS translated the legal notice into filing instructions, and ACE began accepting entries under the corrected numbers at noon on September 23, 2026.

What It Means for Importers

If you import machine parts or plastic components from China and any of your entries between July 1 and September 22, 2026 were filed under the old statistical suffixes without the exclusion applied — or with Section 301 duties paid in full because the system didn't recognize the exclusion — you likely have a refund claim sitting on the table right now.

CBP's guidance spells out the fix: file a Post Summary Correction (PSC) on or after September 23, 2026, if the entry is still within the PSC filing window. If the entry has already liquidated and fallen outside the PSC timeframe, the fallback is a protest, provided you're still inside the 180-day protest deadline. This is the same underlying mechanic we've written about for IEEPA tariff refund claims — the paperwork window is real, but it doesn't stay open forever, and CBP won't chase you down to remind you it's there.

It's also a good moment for a broader gut-check: Section 301 exclusion lists get amended more often than most importers realize, usually in response to exactly this kind of HTS renumbering. If your bill of materials includes any exclusion-eligible Chinese-origin goods, it's worth having your broker periodically re-verify that your classification codes still match the current exclusion language — not just the language that was correct when you first set up the entry.

Practical Next Steps

• Pull entry summaries for Chinese-origin pump, compressor, fan, or plastic-article imports filed between July 1 and September 22, 2026.
• Check whether Section 301 duties were assessed under the old statistical suffixes (8413.91.9065/9085/9096 or 3926.90.9910).
• If duties were paid on goods that now qualify under the corrected exclusion codes, have your broker file a PSC (or protest, if outside the PSC window) to recover the overpayment.
• Ask your broker to build a standing check for Section 301 exclusion/HTS mismatches into your entry review process going forward.

If you're new to importing through South Florida, our complete 2026 guide to importing through Miami covers how classification, tariffs, and broker review fit together from day one.

Frequently Asked Questions

What is CSMS #69990649?

CSMS #69990649 is a Cargo Systems Messaging Service bulletin CBP issued on September 22, 2026, giving importers, brokers, and filers entry-filing instructions for four Section 301 China product exclusions affected by a July 1, 2026 HTSUS statistical reclassification.

Which HTS codes are affected by the September 2026 Section 301 conforming amendment?

The amendment covers statistical reporting numbers 8413.91.9039, 8413.91.9046, 8413.91.9059, and 8413.91.9099 for pump, compressor, and fan parts, and 3926.90.9915 and 3926.90.9920 for other plastic articles, replacing the pre-July 2026 codes 8413.91.9065, 8413.91.9085, 8413.91.9096, and 3926.90.9910.

How do I claim a refund of Section 301 duties under this update?

Importers may file a Post Summary Correction on or after September 23, 2026 for entries still within the PSC filing timeframe, or a protest if the entry has liquidated but remains within the 180-day protest window, per CBP's September 22, 2026 CSMS #69990649 guidance.

When did ACE start accepting entries under the corrected Section 301 exclusion codes?

ACE functionality for accepting the conforming amendment became effective at noon Eastern Time on September 23, 2026, according to CBP's CSMS #69990649.