Why your entry shows the wrong duty stack: Section 232, IEEPA, Section 301 and Section 122, with worked lines

What is a duty stack, and why does the entry date decide it?

A duty stack is every charge on one entry line: the base rate from chapters 1 to 97 of the Harmonized Tariff Schedule plus each additional duty reported under a Chapter 99 heading. On a Form 7501 the Chapter 99 numbers sit above the ordinary tariff number on the same line, and each one carries its own rate.

Three facts decide whether a stack is right.

1. The entry date. Every proclamation, executive order and trade notice applies to goods "entered for consumption, or withdrawn from warehouse for consumption, on or after" a stated time. Two identical shipments a day apart can owe different duty. A stack built with today's tables for an entry filed last year is wrong even if each rate looks familiar.
2. The value each rate applies to. Most additional duties apply to the entered value of the line. Section 232 steel and aluminum duty on derivative articles applied, for a long stretch, only to the value of the metal content, reported on a separate line. Which value is right also changed on a specific date.
3. Which measures exclude which. Some programs switch others off. Content subject to Section 232 steel or aluminum duty was not subject to the IEEPA reciprocal tariff; Section 232 articles were exempt from the Section 122 surcharge and are exempt from the July 2026 Section 301 action. Each exclusion has its own Chapter 99 heading, and a stack that leaves it out charges both duties.

The order CBP tells filers to report the lines in is not the order the money is calculated in. CSMS # 67844987 (February 23, 2026) lists Section 301 first, then Section 122, then Section 232. Each of those rates is still a percentage of a value, added side by side, never a duty on a duty.

Which dates changed the stack?

These are the changes the worked lines below depend on. Each date is the start of the "entered on or after" window in the instrument named.

Behind the IEEPA row sits the Supreme Court's decision in Learning Resources, Inc. v. Trump (February 20, 2026, decided with Trump v. V.O.S. Selections, Inc.), which held that IEEPA does not authorize the President to impose tariffs. Every IEEPA duty in the lines below is refundable; how to claim it is covered in IEEPA refunds: which entries qualify.

Each worked line uses an entered value of $10,000 so the gaps are easy to read. Rates come from the Chapter 99 text: HTS Revision 32 of 2025, in force in December 2025, for the December 2025 entries, and the current release (Revision 21 of 2026) for the 2026 headings.

Worked line 1: why does a steel derivative carry the wrong Section 232 value?

The goods: boltless steel shelving with particleboard shelves, HTS 9403.20.0075, product of Vietnam, base rate free. The invoice and the supplier's cost breakdown put the steel content at $7,000 of the $10,000 entered value. Boltless steel shelving from Vietnam is also covered by an antidumping duty order (Commerce, 89 FR 48555, June 7, 2024), so a real entry of it is type 03 with a case number and a cash deposit. The tables leave the antidumping deposit out to isolate the Chapter 99 stack.

Entered December 15, 2025. Subheading 9403.20.00 was listed in note 16(n) for heading 9903.81.91, which CBP's CSMS # 65236374 describes as derivative steel products where "the Section 232 duty is on the value of the steel content." The same message tells the filer to split the line: the first line carries the value less the steel content, the second carries the steel content. The non-steel line is subject to the reciprocal tariff; the steel line is excluded from it under 9903.01.33.

The third row overpays $2,900 against the documented stack. Split it: $1,400 is extra IEEPA duty, which comes back with the rest of the IEEPA duty through CBP's refund process anyway. The other $1,500 is Section 232 duty charged on value that was not steel. That part is not IEEPA and needs its own correction. The fourth row underpays Section 232 by $1,500 because the steel content was understated, and overpays IEEPA duty by $600 because the reciprocal tariff was charged on $6,000 instead of $3,000. Both are findings. Check this line on the duty calculator.

Entered October 1, 2026. Proclamation 11021 made the Section 232 duty apply "to the full customs value of the imported product, regardless of metal content" from April 6, 2026. In the current schedule, 9403.20.0075 is listed among derivative steel articles in note 16(c)(vii), charged under heading 9903.82.09 at 25 percent. For articles outside chapters 72, 73, 74 and 76, note 16(c) applies the heading only where the metal is at least 15 percent of the article's weight, which a steel-framed shelf unit will usually meet; check the supplier's weight breakdown. The July 2026 Section 301 duty for Vietnam (9903.05.84, +12.5%) does not apply, because note 52(f) exempts derivative articles under the 9903.82 headings through 9903.05.90.

The wrong stack is short by $375 overall, but that hides two errors: Section 232 underpaid by $750 and Section 301 overpaid by $375. A netting audit would miss both. Check this line on the duty calculator.

Worked line 2: why does a Chinese-origin line carry the wrong IEEPA rate?

The goods: an article of plastics, HTS 3926.90.99, product of China, base rate 5.3 percent. The subheading is on the list in note 20(s), so Section 301 duty applies under heading 9903.88.15 at 7.5 percent.

Entered December 15, 2025. Two IEEPA duties applied to Chinese goods. The fentanyl duty under 9903.01.24 had been cut from 20 to 10 percent for goods entered on or after 12:01 a.m. EST November 10, 2025 by Executive Order 14357. The reciprocal duty on Chinese goods was 10 percent under 9903.01.25 from May 14, 2025, per CBP's IEEPA FAQ, with the China-specific heading 9903.01.63 suspended. China fentanyl duty is not in the unstacking list for Section 232 content, which matters for Chinese metal derivatives: it applies to the whole line.

The IEEPA portion ($2,000 right, $3,000 wrong) is refundable in full. The Section 301 and base-rate duty stay owed, so an exclusion claimed without support is an underpayment to correct even after the IEEPA refund lands. Check this line on the duty calculator.

Entered October 1, 2026. The IEEPA headings are inactive in ACE from February 24, 2026, per CSMS # 67834313. The July 2026 Section 301 action adds 12.5 percent for products of China under heading 9903.05.31, and U.S. note 52 says those goods remain subject to any other additional duty in the subchapter, so it stacks with the older Section 301 duty.

A system that has not loaded the July 2026 headings underpays $1,250 a line. That is a prior-disclosure conversation, not a refund one; see how long you have to fix a past entry.

Worked line 3: what happened to lines entered around February 24, 2026?

The goods: cotton T-shirts, HTS 6109.10.00, product of Vietnam, base rate 16.5 percent.

Two instruments met in the same week. CSMS # 67834313 says IEEPA duties "will no longer be collected for goods entered for consumption or withdrawn from warehouse for consumption, on or after 12:00 a.m. eastern time on February 24, 2026." Proclamation 11012 imposed a 10 percent surcharge under Section 122 of the Trade Act of 1974 from 12:01 a.m. EST the same day, through 12:01 a.m. EDT July 24, 2026. Heading 9903.03.02 exempted goods loaded onto a vessel and in transit before February 24 and entered before 12:01 a.m. EST February 28, 2026.

The second row is the trap. The goods escaped IEEPA because of their entry date and escaped Section 122 because of their loading date. A surcharge charged on them is Section 122 duty, not IEEPA duty, so it does not come back through the IEEPA refund process; it needs a post-summary correction before liquidation or a protest after. The last row is an underpayment of $250.

The Section 122 surcharge has its own open question. In Oregon v. United States (Slip Op. 26-47, May 7, 2026), the Court of International Trade held the surcharge unlawful but limited its injunction to the prevailing plaintiffs and declined to issue a universal one. [OWNER REVIEW: has the government appealed Oregon v. United States, and is there any refund route for Section 122 duty paid by importers who were not plaintiffs? Neither was found in a primary source on October 27, 2026; if still unknown, keep this sentence as written.] Keep a list of every 9903.03.01 line you paid on until that is settled. Check these lines on the duty calculator.

Worked line 4: why does an EU line pay more than the floor?

The goods: electric hair dryers, HTS 8516.31.00, product of Germany, base rate 3.9 percent.

Some partners' additional duties are written as a floor: the Chapter 99 rate replaces the combined rate up to a fixed total instead of adding to the base rate. Heading 9903.02.20 covered EU goods with a base rate below 15 percent during the IEEPA reciprocal period; its rate column reads "15%", the total. Heading 9903.05.39 does the same at 10 percent for EU goods entered from July 24, 2026, and note 52 says for those goods "the sum of the column 1 duty rate and the additional ad valorem rate of duty is 10 percent ad valorem." Goods at or above the floor go under the paired heading (9903.02.19, now 9903.05.38) with no additional duty.

The first two wrong stacks overpay $390 a line. The 2025 overpayment is IEEPA duty and comes back through the IEEPA refund process. The 2026 overpayment is Section 301 duty and needs a correction or protest. The third wrong stack underpays $610 because the line went under the at-or-above heading. Floor errors are easy to miss because the total still looks plausible. Note 52(k) also sets out how to compute an ad valorem equivalent when the base rate is specific or compound, so lines with per-kilo or per-unit rates need the same check. Check this line on the duty calculator.

How do I check the stack on my own entries?

1. Pull the lines, not the totals. Export entry lines with entry date, country of origin, HTS number, every Chapter 99 number, the value on each line and the duty on each line. Your broker's monthly entry export usually has this; the entry summaries themselves always do.
2. Group by entry date window. Use the dates in the table above. Lines in the same window should follow the same pattern for the same product and origin.
3. Find split lines. For Section 232 derivatives entered before April 6, 2026, look for pairs of lines with the same HTS number and origin, one with a quantity of zero. A derivative on one line at full value is right only if the metal content was unknown or equal to the entered value; check the file for a content breakdown.
4. Check each exclusion heading. Where a Section 232 heading appears, the matching exclusion should be there too: 9903.01.33 before February 24, 2026, 9903.03.06 from then until July 23, 2026, 9903.05.90 from July 24, 2026.
5. Re-run the rate for the date. Recompute each line with the measures in force on its entry date, using the duty calculator or the Chapter 99 text for that revision of the schedule.
6. Record both directions. List every line where the recomputed duty differs, with the amount and the program. Overpayments and underpayments go on the same list.
7. Route each difference by program. IEEPA amounts go to the IEEPA refund process. Everything else follows the ordinary correction routes in how to recover overpaid import duty. Underpayments go to your broker for a post-summary correction or to counsel for a prior disclosure.

Doing this by hand works for a handful of entries. A post-entry audit tool such as TariffSense reads Form 7501s and broker exports in any layout, rebuilds each line's stack with the measures in force on its entry date, and flags overpayments and underpayments line by line with the reason and the corrected value. Your broker files any correction.

What should I do next on my own entries?

Take ten entries that carry Section 232 metal headings or Chapter 99 lines from 2025, recompute them with the rules for their entry dates, and see whether the differences point one way. If they do, the same cause is probably on every entry from that period, and the rest of the book is worth checking. The post-entry audit guide covers everything else to check on each line. Confirm any correction or disclosure with a licensed customs broker or trade counsel before it is filed.