Got a CBP bill after liquidation? Trace it to the line, then pay or protest

What is a bill after liquidation, and why did it arrive?

Liquidation is CBP's final computation of the duties, taxes and fees on an entry. When that computation comes out higher than the estimated duties you deposited at entry, 19 U.S.C. 1505(b) has CBP collect the increase "together with interest thereon", and the vehicle is a bill. CBP's bill form is CBP Form 6084, which 19 CFR 24.4 calls the "United States Customs Service Bill" (in its rule on deferred alcohol taxes), and 19 CFR 24.3a(d)(1) lists what a bill normally shows: the principal due, the interest computation date, the late payment date, the current interest rate, the interest owed, the CBP office that handles billing errors, and the transaction identifier, which for a liquidation bill is the entry number.

The entry number is the only link the bill gives you to the cause. It does not say which line moved or why. That is the first job, and the one most people skip: a bill paid without being traced is a decision accepted without being read, and the 180-day protest window is the only time that decision can be challenged.

Bills reach importers for a handful of recurring reasons:

• CBP changed the classification or value of a line, usually after a CBP Form 29 notice of action (19 CFR 152.2 requires one when the increase on the entry is over $15).
• A post-summary correction raised the duty and the increase was left to be billed. Under the PSC test as modified by 91 FR 41053, you may wait for the bill at liquidation; interest on the increase is always billed then. A post-summary correction that increases duty has that route.
• An antidumping or countervailing duty entry liquidated at the final assessed rate, after liquidation was suspended.
• Interest only. An entry whose increase you paid before liquidation still carries interest from the original deposit date to the payment date, which comes as its own bill.

Under 19 CFR 159.6, CBP disregards a net difference under $20; anything at or above that is billed.

Which two clocks start, and how do they sit side by side?

Both clocks start at liquidation, and 19 CFR 159.9(c) fixes that date as the date the notice is posted on cbp.gov. The courtesy notice your broker receives is informal. How to check entry liquidation status covers how to find the posted date for a whole export.

Read the first and third rows together. The payment clock is 30 days and the protest clock is six months. Neither waits for the other.

How do you trace the bill back to the line?

The bill gives you an entry number and a total. Turn it into a line in five steps.

1. Split interest from principal. The bill states both. Only the principal tells you which line moved; the interest follows from it.
2. Get the liquidated entry summary. Ask your broker for the entry summary as liquidated, alongside the version filed (and any PSC). The difference between the two, line by line, is what CBP decided.
3. Find the CBP Form 29. If CBP advanced a rate or value, 152.2 required a notice of action naming the difference. If none reached you, ask the broker whether one arrived through ACE.
4. Divide the principal by each line's entered value. A classification change shows up as a principal equal to one line's value times the difference between two duty rates. A value change shows up as the old rate times the added value. When one line fits exactly, you have it.
5. Recompute that line on its entry date. The rate that applied is the one in force on the entry date, including any Chapter 99 duty. The duty calculator shows the stack for a given date; if CBP's figure matches the law, the bill is right and the question is only payment. If it does not, you have a protest.

Worked example: one bill, traced and decided

An illustrative entry with invented figures:

• Entry date November 3, 2025; estimated duties due and deposited on November 17, 2025.
• Line 2: entered value $85,000, declared under an HTS number at 2.0 percent.
• CBP liquidated the entry on September 18, 2026 and issued a bill on September 25, 2026 for principal of $1,615.00 plus interest.

Tracing. $1,615 divided by $85,000 is 1.9 percent. On the liquidated summary, line 1 ($40,000) and line 3 ($12,500) carry the same number, value and duty as filed. Line 2 moved from a 2.0 percent number to a 3.9 percent number, which the CBP Form 29 confirms. The bill is about one classification decision on one line.

Interest. 19 CFR 24.3a(b)(2)(i) runs interest from the date the deposit was due to the liquidation date. With the rates in CBP's quarterly notice (91 FR 60141):

CBP applies 26 U.S.C. 6621 and 6622 (24.3a(c)), so its figure on the bill is the one that counts; the table shows how it is built. The bill is about $1,705.

The dates that follow.

The decision. Suppose your classification file, and a ruling on an identical product, support the 2.0 percent number. You pay $1,705 by October 25, so no delinquency interest runs and the surety hears nothing. You protest line 2's classification before March 17, 2027, citing the entry, the line and the ruling, as how to file a customs protest describes. If CBP allows the protest, 19 CFR 174.29 has it refund the excess, and 1505(b) and (c) add interest and require payment within 30 days of reliquidation.

Suppose instead you leave the bill unpaid while the protest is pending. After October 25, the balance is delinquent and interest runs by 30-day periods from the liquidation date (1505(d)); once the bill is more than 30 days past due, CBP reports it to the surety on a formal demand (24.3a(d)(2)); and if the protest is denied, 28 U.S.C. 2637(a) still requires payment before you can go to court. Holding back the money buys nothing the protest does not already give you.

When is not paying, or paying and not protesting, the right call?

Pay without protest when the trace shows CBP was right. Then the bill is the cheap end of the problem: the other entries carrying the same product under the same number are the expensive part. Entries still open can be corrected by post-summary correction; liquidated ones may call for a prior disclosure. Talk to counsel before the next liquidation brings the next bill.

Ask for a billing adjustment when the liquidation is right and the bill is not, for example an interest period that starts on the wrong date or a payment not credited. 24.3a(d)(1) has the bill name the office for that.

Ask for a voluntary reliquidation when CBP plainly made a mistake and the 90 days of 1501 are still open. It can be quicker than a protest, but it is CBP's choice, so file the protest anyway if the 180 days are at risk.

Protest before paying is lawful, and some importers do it when the bill is large and the protest is strong. Weigh it against the delinquency interest, the surety demand, and the fact that a denial leads to court only after payment. Confirm the choice with a licensed customs broker or trade counsel.

Why does one bill call for checking more than one entry?

A bill is CBP telling you its view of a line on one entry. The same product usually crossed the border many times under the same number. A line-level audit of the export finds the siblings: entries still inside their PSC window, entries that liquidated as entered and will not be billed, and entries due to liquidate next month. TariffSense reads entry summaries and broker entry exports, recomputes each line's duty on its entry date and flags where the declared duty and the law diverge, in either direction, so a bill can be matched to the line that caused it and to every other line with the same cause. The post-entry audit page shows what goes in and what comes back. The post-entry audit pillar has the line checks.

What should you do this week if a bill just arrived?

1. Write down the liquidation date from the cbp.gov notice and the bill's issue date. Put the bill's due date (issue date plus 30 days) and the protest deadline (liquidation date plus 180 days) in the calendar.
2. Get the filed and liquidated entry summaries and any Form 29 from your broker, and trace the principal to the line using the steps above.
3. Recompute that line on its entry date. Decide: billing error, voluntary reliquidation request, protest, or no dispute.
4. Pay by the due date unless counsel advises otherwise, and confirm the importer's ACH Refund details are on file in the ACE Portal so any protest refund can be delivered.
5. Search the rest of the export for the same product and HTS number, and fix the open entries before they liquidate.