Post-entry customs audit: what to check on every line of a Form 7501

What is a post-entry customs audit?

A post-entry customs audit is a review of entries after they have been filed, line by line, to confirm that what was declared on the entry summary was right on the day the goods were entered. For US imports the entry summary is CBP Form 7501, and every line on it carries a set of claims: this product is classified here, this rate applies, these additional duties stack on top, this is the value, this is the quantity, this is where it was made, this trade agreement applies, these fees are due.

The importer of record owns those claims. 19 U.S.C. 1484 makes the importer responsible for using reasonable care to declare the value, classification and rate of duty. A broker prepares and transmits the entry, but the liability for a wrong number sits with the importer. That is why the audit is worth doing yourself rather than waiting for CBP.

Three numbers from CBP's own trade statistics page explain why this matters more now than it did two years ago. CBP reports $216.7 billion in duties, taxes and fees collected in FY 2025, against $88.1 billion in FY 2024. It reports that its entry summary reviews recovered a net $34.4 billion in FY 2025, against $668 million the year before. And it reports 465 audits completed in FY 2025, against 50,084,153 entry summaries. CBP labels these figures as for monitoring purposes, updated July 27, 2026. More money rides on every line, CBP is reviewing lines far more than before, and a full CBP audit remains rare enough that most errors are found only by the importer or by a reviewer looking at one entry.

An audit has two outcomes and both count. Overpayments become refund claims. Underpayments become corrections or prior disclosures. A good audit reports both, because a refund claim on a line that also hides an underpayment invites the review you were hoping to avoid.

Why audit from the broker's full entry export instead of a sample?

Sampling assumes errors are random. On customs entries they are not. Most line errors come from one of three places, and each one repeats.

• The product master. If a part was set up with the wrong HTS number or the wrong origin, every entry of that part carries the same error until someone fixes the master record.
• The broker's filing template. If the broker's software applies a Chapter 99 heading to a family of HTS numbers, every entry of those products inherits the same stack, right or wrong.
• A date boundary. Duty measures switch on and off on specific dates. The Section 232 rate on steel and aluminum rose from 25 percent to 50 percent for goods entered on or after June 4, 2025 (Proclamation 10947). Executive Order 14389 ended the IEEPA duties, and CBP stopped collecting them on goods entered from February 24, 2026 (CSMS # 67834313). The Section 122 surcharge started the same day (Proclamation 11012) and lapsed on July 24, 2026, when a Section 301 action on forced labor took over (USTR notice, 91 FR 47318). For goods entered from April 6, 2026, Section 232 duty applies to the full customs value regardless of metal content (Proclamation 11021). Entries filed in the days around each boundary are the ones most likely to carry the old stack.

A sample of twenty entries can miss every one of those. The broker's monthly or quarterly entry export lists every entry and every line, with HTS numbers, Chapter 99 headings, values, quantities, rates and duty amounts. Auditing all of it costs little more than auditing a sample once the export is loaded, and it turns an error you found once into a list of every entry where it happened. That list is what you need to decide whether one post-summary correction, a batch of protests or a prior disclosure is the right response.

Pair the export with the invoices and packing lists where you can. The rate checks need only the entry data. The value, quantity and origin checks need the documents the entry was built from. For how to line the three sources up, see reconciling broker entry exports with invoices and your ERP.

What gets checked on every line?

Each check compares a field on the 7501 with a rule or with another document. The field names below follow CBP's Form 7501 instructions (revision 02/26). For the full block-by-block reference, see Form 7501 field by field.

The sections that follow take each row in turn.

How do you check the classification on a line?

Classification comes first because everything else hangs off it. The 10-digit HTS number in column 33A sets the base rate, decides whether a Section 232 or Section 301 measure applies, decides the unit of quantity in column 35 and decides whether an AD/CVD order might cover the product.

The check is simple to describe and hard to do at scale. Read the description in column 32 and the product data behind it, then confirm that the heading follows the General Rules of Interpretation in the Harmonized Tariff Schedule. Where a CBP binding ruling covers the product, the 7501 instructions require the ruling number under the HTS number with the prefix "RLNG", and an item that is classified the same way but not covered by the ruling must go on its own line. A ruling number on a line whose product does not match the ruling is a finding.

Patterns worth searching the whole export for:

• The same part number under two HTS numbers. One of them is probably wrong, and the error runs in whichever direction the rates differ.
• Headings that changed in an HTS revision. A product master that still holds a retired statistical suffix will be rejected or mapped by the broker, sometimes to a heading with a different rate.
• Parts entered under the heading of the finished article, or the reverse.
• Sets classified under GRI 3(b) or 3(c). The 7501 instructions require the set's rate on an "X" line and every article in the set on its own "V" line.

A classification change moves money in both directions at once: the base rate, the Chapter 99 stack and sometimes the AD/CVD exposure. Work out the whole stack for the corrected heading before you call the finding an overpayment.

How do you check the rate and the Chapter 99 stack?

The base rate is the rate printed in the HTS for the heading on the date of entry. The Chapter 99 stack is everything added to it. Each additional measure is reported as its own Chapter 99 heading on the same entry summary line, with its own rate and its own duty amount in column 38.

The programs that have stacked on US entries in the last two years each have their own trigger:

• Section 232 applies by product and metal. For derivative articles entered before April 6, 2026 the duty was generally charged on the value of the metal content; from that date it applies to the full customs value regardless of metal content (Proclamation 11021). Blocks 21 to 24 of the 7501 (country of melt and pour, primary and secondary country of smelt, country of cast) must be completed for covered steel and aluminum articles even when the Section 232 duty does not apply, according to the 7501 instructions.
• Section 301 applies to products of China on the USTR lists, with product exclusions that are written by description, not by HTS number alone. A second Section 301 action, on forced labor, adds 10 or 12.5 percent on products of 60 economies, China included, for goods entered from July 24, 2026 (headings 9903.05.20 to 9903.05.84), with Section 232 metal articles exempt.
• IEEPA duties applied to products of named countries under a series of executive orders and stopped applying to goods entered from February 24, 2026 (Executive Order 14389). On February 20, 2026 the Supreme Court held that IEEPA does not authorize tariffs (Learning Resources, Inc. v. Trump, No. 24-1287), and CBP now refunds those duties through CAPE.
• Section 122 imposed a 10 percent surcharge on goods entered from February 24, 2026 until it lapsed on July 24, 2026 (Proclamation 11012), with exemptions reported under their own headings.

The audit question for each line is the same: on this entry date, for this HTS number, this origin and this metal content, which measures applied, at what rate, with which exceptions and in what order? You can check one line by hand with the duty calculator, which shows the full stack for a code, an origin and a date. The stacking rules themselves, with worked lines for each program, are on why your entry shows the wrong duty stack.

A worked line: aluminum plate from China, entered June 12, 2025

Take one illustrative line: aluminum plate, HTS 7606.11.3030, product of China, entered value $10,000, entered June 12, 2025. The stack on that date:

Three errors that an audit of this one line can find, in both directions:

1. The old Section 232 rate. Proclamation 10947 raised the aluminum rate from 25 percent to 50 percent for goods entered on or after June 4, 2025. A line filed at 25 percent eight days later shows $2,500 under 9903.85.02 instead of $5,000. That is a $2,500 underpayment, plus interest, and every entry of the same product in the days after June 4 probably carries it too.
2. The reciprocal duty charged instead of the exception. The line should report 9903.01.33 at 0 percent, the exception for articles subject to Section 232. A line that reports the reciprocal heading at its rate instead overpaid by that rate times $10,000.
3. IEEPA duties paid at all. The $2,000 under 9903.01.24 is an IEEPA duty. Since the Supreme Court's decision, it is refundable with interest through CBP's CAPE process if the entry is within CAPE's scope. See which IEEPA entries qualify for a refund.

The same product entered on another date has a different stack, and the same date with a different metal content or origin has a different stack again. That is why the check is per line and per date, not per product.

How do you check the value on a line?

Column 36A holds the entered value in US dollars, as defined in 19 U.S.C. 1401a, rounded to the nearest whole dollar. For most imports that is the transaction value: the price actually paid or payable, plus five additions listed in 19 CFR 152.103(b) when they are not already in the price:

1. packing costs incurred by the buyer;
2. selling commissions incurred by the buyer;
3. the apportioned value of any assist (tooling, molds, materials or engineering supplied to the maker free or at reduced cost);
4. royalties and license fees the buyer must pay as a condition of the sale;
5. proceeds of any resale that accrue to the seller.

Column 36B holds the charges: freight, insurance and other costs of bringing the goods from the port of export to the first US port. Those are reported separately and are not part of the dutiable value. Column 36C says whether buyer and seller are related.

Value errors that show up line by line:

• Freight or insurance inside the entered value. A CIF invoice value entered without deducting international freight overstates the value and every ad valorem duty on the line, including each Chapter 99 layer. On a line with a 98 percent stack, that error costs almost a dollar of duty for every dollar of freight.
• Assists and royalties left out. Tooling paid by the buyer, or a royalty tied to the sale, belongs in the value. Leaving it out is an underpayment.
• Currency conversion. The invoice currency converted at the wrong rate or on the wrong date moves every line on the invoice by the same percentage.
• Value on the wrong line. CBP's CAPE guidance (CSMS # 68340863) repeats that the entered value belongs on the Chapter 1–97 classification, not on a Chapter 99 line. Value reported on the Chapter 99 number breaks the line's arithmetic.
• Invoice total against block 39. The sum of entered values should reconcile to the invoices after the deductions above. A gap that no deduction explains is a finding.

Where the value is right but some layers apply only to part of it, as with Section 232 duties computed on metal content for derivative articles entered before April 6, 2026, check that the value split between the lines matches the supplier's content declaration.

How do you check quantity and unit?

Column 35 holds the net quantity in the unit the HTS specifies for that number, with the unit shown after the figure. Where the HTS gives two units, both are reported. Where it shows "X", no quantity is reported, though gross weight in column 34A still is.

Quantity matters to duty in two ways. On a specific or compound rate (cents per kilogram, dollars per dozen), the duty is the quantity times the rate, so a wrong quantity is a wrong duty. On any line, quantity is what CBP and an auditor compare against the invoice and packing list to see whether the value per unit makes sense.

The findings are concrete: a quantity reported in pieces where the HTS unit is kilograms, a dozen reported as a unit, a net weight that is really a gross weight, or a quantity that does not match the packing list. Each one is checkable from the documents, and each one repeats across every entry built from the same product record.

How do you check the country of origin?

Block 10 records the country of origin as an ISO code. The 7501 instructions define origin as the country of manufacture, production or growth, or, where more than one country was involved, the country where the article last underwent a substantial transformation. When an invoice is issued in or the goods are shipped from another country, the actual origin is reported, not the country of invoice or export. When an entry covers several origins, block 10 says "MULTI" and each line carries its own code in column 31 with the prefix "O".

Origin decides whether Section 301 applies, which IEEPA order applied before February 24, 2026, whether an AD/CVD order covers the goods and whether a trade-agreement rate is available. An origin error is rarely a small one.

Two patterns to look for in the export:

• Country of export reported as origin. Goods shipped through a third country or invoiced by a trading company often carry the export country by mistake. Block 14 (exporting country) exists so the two can differ.
• Origin that changes between entries of the same part without a change of supplier or process. One of the entries is wrong.

For steel and aluminum articles, the melt-and-pour and smelt countries in blocks 21 to 24 are separate from origin and should agree with mill certificates.

How do you check trade-agreement claims and special program indicators?

A claim for a preferential rate is made with a special program indicator in column 31, placed right before the HTS number it applies to. The indicator tells CBP the goods qualify under an agreement such as USMCA, and for originating goods it can also remove the merchandise processing fee: 19 CFR 24.23(c)(3) exempts goods originating under General Note 11 of the HTS (USMCA) from the ad valorem MPF.

The audit checks both directions:

• A claim without support. The importer must hold a valid certification of origin when a claim is made. A claim on a line whose goods do not meet the rule of origin, or with no certification on file, is an underpayment of the full general rate plus the MPF.
• Qualifying goods entered without a claim. This is one of the most common overpayments. Under 19 U.S.C. 1520(d), an importer can claim the preference after the fact for goods that qualified under the agreements the statute lists, including USMCA, within one year after the date of importation, with a declaration and the certification of origin (19 CFR 182.31 and 182.32 for USMCA). One year is short, and it runs from importation, not from liquidation.

How do you check AD/CVD lines?

Antidumping and countervailing duty lines carry a Commerce case number under the HTS number in column 33B, the AD or CVD rate in column 37B and usually entry type 03. The 7501 instructions set the order for choosing the case number: the exporter's own case if it has one, then the producer's or the exporter-producer combination's, and only then the "all others" case with the 000 suffix.

The checks:

• Scope. Is the product within the written scope of the order? Scope is set by Commerce's description, not by the HTS number, which is listed for convenience.
• Case number and rate. Does the case number match the actual exporter and producer on the invoice? Using an "all others" case for an exporter with its own lower rate overpays the deposit; using another company's lower rate underpays it.
• Subject goods entered without a case. Entry type 01 on goods that fall within an order is the most serious finding on this row.

AD/CVD entries usually stay unliquidated until Commerce issues liquidation instructions, so the final duty may differ from the deposit. Track those entries separately; their deadlines run from a different event.

How do you check the MPF and HMF?

Two fees appear on almost every formal entry.

• Merchandise processing fee (MPF). 19 CFR 24.23 sets it at 0.3464 percent of the value of formally entered merchandise, subject to a minimum and a maximum per entry that CBP adjusts for inflation every fiscal year. For FY 2027, required from October 1, 2026, CBP Dec. 26-14 sets the minimum at $34.58 and the maximum at $670.86. An entry from an earlier fiscal year is checked against that year's table.
• Harbor maintenance fee (HMF). 19 CFR 24.24 sets it at 0.125 percent of the value of commercial cargo loaded or unloaded at a covered port, which means vessel cargo. The 7501 instructions note that HMF of $3 or less is not collected when it is the only payment due.

The MPF is reported at line level and capped at entry level, so a line-by-line calculation that is never capped overstates it. HMF on air or truck shipments is an overpayment. Missing HMF on vessel cargo is an underpayment. MPF charged on USMCA-originating goods with a valid claim is an overpayment, and MPF missing on goods whose USMCA claim fails is an underpayment that grows with the claim.

Where do overpayment and underpayment hide in stacked lines?

On a line with one rate, an error moves the duty by a few percent. On a line with four or five stacked layers, the same error moves it by the whole stack. The places to look:

1. Entries filed around a date boundary, carrying the stack from before or after the change. The aluminum example above is one; every rate change creates a batch of these.
2. An exception claimed under the wrong program. Exceptions are program-specific: the exception from the IEEPA reciprocal duty for Section 232 articles did not remove the Section 301 duty. A line that reports an exception heading for a program whose conditions it does not meet underpays; a line that misses an exception it qualified for overpays.
3. The whole value under a layer that applies to part of it, or the reverse. Section 232 duties on derivative articles entered before April 6, 2026 were computed on metal content, with the non-metal part reported on its own line; from that date they apply to the full value. Getting the split wrong, or keeping it after April 6, moves the duty on both lines.
4. A layer reported twice, for example the same Chapter 99 heading on two lines for one article.
5. A product exclusion whose description does not fit the goods. Section 301 exclusions are written by product description. An exclusion heading on a line whose goods fall outside the description is an underpayment of the full Section 301 rate.
6. Valuation errors multiplied by the stack. Freight left in the value of a line with a 98 percent stack costs almost a dollar of duty per dollar of freight.
7. Origin errors that switch programs on or off. A product of China reported as a product of Vietnam avoids Section 301; the reverse adds it.

Most of these are invisible on a single entry and obvious across a year of them, which is the argument for auditing the full export.

What do you do with each finding?

A finding becomes useful when it is tied to an entry, a dollar amount and a deadline. Work through it in this order:

1. Confirm the finding against the documents: the invoice, the certificate, the ruling, the mill certificate. Write down the rule and the source.
2. List every entry with the same pattern. Search the export for the same part, HTS number, supplier or date range.
3. Find each entry's liquidation status and date. Liquidation starts the protest clock and closes the post-summary correction window. See how long you have to fix a past entry.
4. Choose the route for each entry. Overpayments on unliquidated entries go by post-summary correction; on liquidated entries, by protest within 180 days of liquidation; unclaimed trade-agreement preference, by a 1520(d) claim within one year of importation; IEEPA duties, through CAPE. See how to recover overpaid import duty for the decision table.
5. Correct underpayments, too. On an unliquidated entry a post-summary correction pays the difference. Where entries have liquidated or the error is systemic, a prior disclosure under 19 CFR 162.74 reports it to CBP before a formal investigation begins. When a CBP request for information arrives first, see CF-28 and CF-29: how to audit yourself before CBP asks.
6. Fix the source. Correct the product master, the broker's template or the supplier's declaration, so the next entry is right.

Filing stays with your broker or your own filer, and decisions that involve a protest or a disclosure are worth confirming with a licensed customs broker or trade counsel.

How does TariffSense fit into a post-entry audit?

TariffSense does the reading and checking described on this page. It reads Form 7501 lines from entry summaries and broker entry exports, pairs them with invoices and packing lists where they are provided and checks each line's classification, duty rate and Chapter 99 stack, value, quantity, origin, trade-agreement claim and AD/CVD exposure against the measures in force on that entry's date. Each finding states what was declared, what the rule says and the corrected value, in both directions. Filing stays with your broker. The post-entry audit page describes what goes in and what comes back. For Canadian entries, the same line-by-line approach is in auditing CAD/B3 entries after accounting. If you are comparing ways to run this work, see post-entry audit tools and duty recovery firms compared.

What should you do next on your own entries?

Ask your broker for the full entry export for the last twelve months, with every line, every Chapter 99 heading and every liquidation date. Sort it by entry date and mark the entries that are still unliquidated: those are the ones where a post-summary correction is still possible. Then take your five highest-duty products and check one entry of each against the rules for its entry date, starting with the Chapter 99 stack. If one of them is wrong, search the export for every other entry with the same product and date range before you decide how to correct it.