What is the penalty for a wrong HTS code on past entries?

Why does a wrong HTS code cost more than the rate difference?

Because the HTS number does not just pick a general rate. It decides which of the additional duties apply to the line. A Section 301 duty on Chinese goods applies only to the subheadings listed in U.S. note 20 to chapter 99. A Section 232 derivative duty applies to the subheadings listed in note 16. Whether an antidumping or countervailing duty order is even considered often starts from the HTS number on the line. Some partners' duties are floors that top the general rate up to a fixed total, so the general rate stops mattering below the floor. A trade-agreement claim is made per HTS number, and the merchandise processing fee exemption follows that claim.

So the cost of a misclassification is the gap between two complete stacks, each built for the entry date of the line. Comparing column 1 rates alone can point the wrong way, as the line below shows. How the stack is built and where it goes wrong for other reasons is in why your entry shows the wrong duty stack.

What does one misclassified line cost, worked both ways?

The goods: lidded plastic boxes, product of China, $80,000 entered value, one line, by ocean to a listed port, entered August 14, 2026, duties deposited with the entry summary on August 28, 2026. Plastic boxes sit on the border between two headings: 3923.10.90, boxes and cases of plastics of the kind used for the conveyance or packing of goods (general rate 3 percent), and 3924.90.56, other household articles of plastics (3.4 percent), both from HTS Chapter 39, Revision 22. Which is right depends on the design and use of the actual product and on CBP's rulings for similar goods, which is the comparison HS classification lays out heading by heading; the numbers below show what each mistake costs. Illustrative figures.

The rates are from HTS Chapter 99, Revision 22: note 20(e) applies 25 percent under 9903.88.03 to the subheadings listed in note 20(f), heading 9903.88.15 adds 7.5 percent for the subheadings in note 20(s), and heading 9903.05.31 adds 12.5 percent to products of China under note 52.

If the right code is 3923.10.90 and the entry used 3924.90.56, the importer underpaid $13,680, or 17.1 percent of the value. Look at the parts: the general rate on the filed code is 0.4 points higher, so a reviewer who compares column 1 alone sees an overpayment of $320. The underpayment comes entirely from the Section 301 list.

If the right code is 3924.90.56 and the entry used 3923.10.90, the importer overpaid the same $13,680. That is a refund, but only if a correction or protest is filed in time.

The same pair of codes costs a different amount on another origin or another date. Before July 24, 2026 the 9903.05.31 layer did not exist, and for goods of a country with no Section 301 list duty the gap shrinks to the 0.4-point difference in general rates. Rebuild the stack for each line's own entry date; the duty calculator does that for one line at a time.

How much interest does an underpayment add?

19 U.S.C. 1505(c) says interest on an underpayment of duties, fees or interest accrues "from the date the importer of record is required to deposit estimated duties, fees, and interest to the date of liquidation or reliquidation." The rate is the IRS underpayment rate under 26 U.S.C. 6621 and 6622, which CBP republishes each quarter. The notice of September 22, 2026 gives:

For the worked line, interest starts on August 28, 2026. CBP's post-summary correction page refers to the 314-day liquidation cycle, which puts liquidation on June 24, 2027. That is 300 days. At 7 percent compounded daily, and assuming the rate stays at 7 percent through the first half of 2027 (it has not been set yet), the interest on $13,680 comes to about $810. Interest is small next to the duty in the first year; it matters more when an error runs for several years of entries, and it keeps running on a bill that is not paid within 30 days of issue (1505(b) and (d)).

Do the fees change when the code changes?

Usually not. The merchandise processing fee is 0.3464 percent of entered value (19 CFR 24.23(b)(1)), here $277.12, inside the fiscal year 2026 limits of $33.58 and $651.50 set by 90 FR 34665. The harbor maintenance fee is 0.125 percent of the same value. A change of HTS number alone moves neither.

Fees do move when the new code changes something else on the line:

• A trade-agreement claim. Rules of origin are written by HTS number. If the right code fails a rule the filed code met, the special program indicator falls away and so does the MPF exemption in 24.23(c), as well as the preferential duty rate.
• A chapter 98 claim that the right classification does not support, since chapter 98 articles are exempt from the MPF.
• Value. A reclassification that comes with a value correction changes both fees in proportion, unless the MPF is at its minimum or maximum.

How each fee is computed, and the fee errors audits find on their own, is in how the merchandise processing fee is calculated.

What is the penalty for a wrong HTS code under 19 U.S.C. 1592?

19 U.S.C. 1592 penalizes entering goods by means of a material false statement or omission through fraud, gross negligence or negligence. The maximums in 1592(c), applied to the worked line's $13,680 loss of duty:

These are ceilings. CBP must establish the violation and the culpability, and it applies its own mitigation guidelines before assessing an amount; the way CBP sizes an actual penalty is in how CBP sizes a Section 1592 penalty. Two rules hold whatever the penalty: 1592(d) requires the lost duties to be restored "whether or not a monetary penalty is assessed," and 19 U.S.C. 1621 gives CBP five years from the violation, or from discovery for fraud, to bring the action.

A prior disclosure made before, or without knowledge of, a formal investigation caps the penalty for a negligent or grossly negligent violation at interest on the unpaid duty "computed from the date of liquidation," provided the duty is tendered (1592(c)(4)(B)). When to disclose and how is in prior disclosure after you find an underpayment. Whether a particular error was negligent is a question for counsel, not arithmetic.

When does a misclassification cost nothing in duty?

Change the origin. The same boxes, product of Germany, entered August 14, 2026. EU goods with a column 1 rate under 10 percent go under heading 9903.05.39, which lifts the total to 10 percent (U.S. note 52; the floor mechanics and the errors they cause are in why your entry shows the wrong duty stack). Both 3 percent and 3.4 percent are under the floor, so either code lands at 10 percent: $8,000 of duty either way. The misclassification changes the statistics, not the money.

It is still an error to correct. Section 1592(c) prices a negligent violation that "did not affect the assessment of duties" at up to 20 percent of dutiable value, here $16,000, which is more than the duty on the line. And the duty effect can appear later without anyone touching the entry: a code that falls on the other side of a floor, or onto a list that changes, carries a different stack on the next entry date.

How do I find misclassification exposure in my entry export?

1. Find the inconsistencies first. Group lines by part number or SKU and by description. Every product entered under more than one HTS number is a finding by definition: at most one of the codes is right.
2. Settle the right code for each product that matters, by the General Rules of Interpretation and CBP rulings on similar goods; how to audit HTS codes on past entries covers the method and binding rulings and CROSS when a ruling binds you.
3. Rebuild both stacks per line for its entry date: general rate, every Chapter 99 heading the code triggers, any AD/CVD scope, and the trade-agreement claim.
4. Price the gap. Difference in stack times entered value, per line, kept by direction. Overpayments and underpayments go on the same list; netting them hides both.
5. Split by liquidation status. Unliquidated lines can go on a post-summary correction within 300 days of entry and at least 15 days before scheduled liquidation; for the worked line that is June 9, 2027, the earlier of the two. Overpaid liquidated lines need a protest within 180 days of liquidation (19 U.S.C. 1514). Underpaid liquidated lines are a prior disclosure conversation. The full set of windows is in how long you have to fix a past entry.
6. Add interest and fee effects to the underpayments, and note any line where the code change also removes a trade-agreement or chapter 98 claim.
7. Fix the source. Update the classification in the product master and the broker's database so the next entry does not repeat it.

The rest of the line checks are in the post-entry audit guide. TariffSense reads entry summaries and broker exports, flags products entered under more than one HTS number, rebuilds the duty stack under the filed and alternative codes for each entry date, and reports the difference per line in both directions. Classification decisions, corrections and disclosures stay with your team, your broker and counsel.