A post-summary correction that increases duty: windows, ACH payment, interest and prior disclosure

When is a post-summary correction the right route for an underpayment?

When three things are true: the entry has not liquidated, it is still inside the filing window, and the error sits in data a PSC is allowed to change. Under those conditions the underpayment is settled inside the entry itself: the PSC replaces the entry summary, the entry liquidates at the corrected duty, and the only extra cost is interest.

CBP's PSC page calls the PSC the sole method for the trade to correct an ACE entry summary electronically before liquidation, and ties the duty to file it to the importer's legal obligation to correct an entry under 19 U.S.C. 1484 and 1485. Most of what is written about PSCs is about getting money back. This page is about the other direction: a line-level audit found that a line was declared at a lower duty than the law required on its entry date, and the entry is still open.

Overpayments on the same entries are covered on how to recover overpaid import duty. Underpayments on entries that have already liquidated are covered on prior disclosure after you find an underpayment. Confirm any filing with your broker or trade counsel.

How long is the window, and what stretches it?

The PSC test, republished in full by CBP on July 6, 2026 (91 FR 41053), sets the window as 300 days from the date of entry or 15 days before the scheduled liquidation date, whichever is earlier. ACE rejects a PSC filed outside it.

Two exceptions are written into the notice:

• Liquidation extended at the importer's request. If you ask for and are granted an extension under 19 CFR 159.12, the 300-day limit falls away and the PSC must be filed at least 15 days before the new scheduled liquidation date.
• Liquidation suspended beyond 300 days. Entries whose liquidation is suspended past day 300 with a listed suspension basis (CVD, ADD or AD/CVD suspend, subject to EAPA, or subject to a court injunction) can take a PSC outside the 300 days. The notice says CBP had allowed this in practice since 2022 and formalizes it.

The outer wall is liquidation itself. Under 19 CFR 159.11, an entry not liquidated within one year of entry is deemed liquidated at the duty asserted by the importer, and the PSC notice reads that as the duty in the most recently accepted PSC. CBP's PSC page refers to the normal 314-day liquidation cycle, and 15 days before day 314 is day 299, so on an entry on that cycle the 15-day limit falls one day before day 300. Treat day 299 as the last safe day unless you know the scheduled liquidation date is later.

What else must be true before ACE accepts the PSC?

The notice and CBP's PSC page set conditions on the entry summary, or on the last PSC filed against it. For an underpayment, it helps to sort them by what you can fix and what you cannot.

Conditions you control. The entry summary has to be paid and in CBP control, which means placed on a statement, before a PSC on it is accepted. On a periodic monthly statement the statement itself has to be paid, and CBP's page warns that payment may not reach CBP until up to 45 days after the entry date. Each PSC also needs at least one reason code and a description of the change.

Conditions that close the route. ACE refuses a PSC on an entry that is liquidated, not in accepted status, under CBP review (the response reads "PSC not allowed under CBP Review") or associated with a protest. On an entry flagged for reconciliation, a PSC can still change data the flag does not cover, but not the flagged issue.

A condition specific to IEEPA refunds. An entry already listed on a CAPE Declaration cannot take a PSC. CBP's IEEPA refund guidance says to file any PSC for a non-IEEPA issue before the entry goes on the Declaration; after that, corrections go to a protest or prior disclosure once the entry liquidates. If an audit finds an underpayment on an entry you plan to put on a CAPE Declaration, correct it first.

CBP sets no cap on the number of PSCs per entry within the window, except that PSCs that have gone through CBP team review are not eligible for repeat submissions, according to its PSC page.

What can a PSC not change?

The notice lists the data elements that cannot be changed by PSC: the importer of record, the date of entry, the date of entry summary, the bond, the surety code, the consolidated summary indicator, any data that would turn a type 23 (temporary importation under bond) entry into another type or the reverse, the port of entry, the cargo release certification and live entry indicators, the 1520(d) trade-agreement indicator, the reconciliation issue code, the preliminary statement print date, the periodic monthly statement, the statement client branch, the location of goods code and any release detail. The entry type can change only between 01 and 03.

Two consequences matter for underpayments. First, a PSC is a complete replacement of the data, not of the history: the notice says obligations that vested under the original entry summary, such as liquidated damages for a late summary, stay in place. Second, an underpayment caused by one of the fixed fields, for example goods entered under the wrong importer of record, cannot be fixed by PSC. CBP's page routes an importer-of-record change through CBP Form 3347 before any PSC.

How is the increase paid?

From August 5, 2026, by ACH only. The notice ends check and cash payment for PSC increases and requires enrollment in either ACH Debit or ACH Credit. CBP's ACH page makes both options available only to filers on ABI statement processing, so the enrollment question usually lands with whoever pays the statements, often the broker; settle it before the first increase is due. Then you choose when to pay:

AD/CVD is the exception: an increase in antidumping or countervailing duty must be paid by ACH within three business days of submitting the PSC.

Read the last column against the audit calendar. Line checks rarely finish in one pass: classification findings come first, valuation findings later, once the freight bills and assist records are in. If the first PSC's increase is still unpaid when a later finding turns up an overpaid line on the same entry, ACE will not take the second PSC until the first increase has been paid in full and processed. On an entry near day 300 that wait can use up the window, and the refund then has to come by protest after liquidation.

How is the interest worked out?

The notice is explicit: interest on a PSC increase is not accepted before liquidation. CBP computes it at liquidation and bills it. The rule it follows is 19 CFR 24.3a(b)(2): where an additional deposit made before liquidation turns out to be the correct balance, interest runs on that amount from the date the original deposit was due to the date the additional deposit was made; where it is not paid before liquidation, interest runs to the liquidation date. The rate is the IRS underpayment rate for each quarter, which CBP publishes in the Federal Register.

An illustrative line, with invented figures:

• Entry date March 19, 2026. Estimated duties were due, and paid, on April 2, 2026.
• Line 003: entered value $60,000, declared under a number at 2.5%. The audit on November 3, 2026 finds the goods belong under a number at 9%. Increase: $3,900.
• Day 300 is January 13, 2027. If the entry is scheduled to liquidate on January 29, 2027, the 15-day cutoff is January 14, so January 13 governs.

CBP's quarterly notice (91 FR 60141) gives the underpayment rate as 6 percent from April 1 to June 30, 2026 and 7 percent from July 1 to December 31, 2026.

CBP applies the rates under 26 U.S.C. 6621 and 6622 (19 CFR 24.3a(c)), so its bill is the figure that counts; the table shows the size of the choice, not the bill. A bill not paid within 30 days becomes delinquent and accrues interest in 30-day periods (19 U.S.C. 1505(d)).

How does a PSC sit next to a prior disclosure?

They do different jobs, and an audit that finds a pattern usually needs both.

A PSC corrects one unliquidated entry. It changes the data, pays the duty and lets the entry liquidate at the right amount. Nothing in the PSC notice treats it as a disclosure of a violation, and the notice keeps penalties in view: a participant may face civil and criminal penalties, administrative sanctions or liquidated damages for, among other things, failure to exercise reasonable care or failure to deposit estimated duties on time.

A prior disclosure addresses the violation. Under 19 CFR 162.74(a), it is made when the importer discloses the circumstances of a violation of 19 U.S.C. 1592 before, or without knowledge of, the start of a formal investigation, and tenders the actual loss of duties. For a negligent or grossly negligent violation that is disclosed and paid, 1592(c)(4) limits the penalty to interest on the unpaid duties.

The usual shape of an audit finding is a cause that runs across months: the same product under the same wrong number on every entry since a date. Some of those entries are still inside the PSC window, some have liquidated and some are in between. The split looks like this:

1. Unliquidated and inside the window: PSC, with payment by ACH. List these entries in the disclosure too, so the disclosure describes the whole cause.
2. Unliquidated but past day 300: no PSC. These go into the disclosure and are collected as CBP directs.
3. Liquidated: prior disclosure with tender of the actual loss. The scoping work is on prior disclosure after you find an underpayment.

Whether to disclose is a counsel decision. What the audit contributes is the table: every affected entry, its line, the duty declared, the duty owed and the entry's status on the day you file. Doing the PSCs without asking that question leaves the liquidated entries uncorrected, which is the part a CBP review is most likely to find.

What should the audit hand to the broker?

For each underpaid line on an unliquidated entry: the entry number and entry date, the line number, the box that was wrong (usually column 33A for the HTS number, 36A for the value or 35 for the quantity), the declared and corrected figures, the dollar increase and the PSC deadline. Form 7501 field by field explains each box. Add the overpaid lines on the same entries, because one PSC carries both and the net is what moves.

TariffSense reads entry summaries and broker entry exports, checks every line against the measures in force on its entry date and returns findings in both directions, with the entry date, line number and liquidation status attached, so the entries still inside the PSC window are visible at a glance. The post-entry audit page shows the output; the post-entry audit pillar explains the checks. To confirm the rate a line should have carried, look it up for the entry date in the duty calculator. The PSC itself is filed by your broker.

What should you do next on your own entries?

List every entry from the last 300 days with its entry date and scheduled liquidation date; how to check entry liquidation status explains how to pull them. Run the line checks on those entries first, because they are the only ones a PSC can still reach. Confirm that your ACH Debit or ACH Credit enrollment is in place before the first increase. For each underpaid line, decide with your broker whether to pay at filing or wait for the bill, bearing in mind that an unpaid increase stops any further PSC on that entry. Then look at the cause behind each finding: if it also reaches entries that have liquidated, take the full list to counsel before filing.