Section 338 Canada T-Minus 1: ACE Summary Acceptance vs 3461 Transmission, 19 CFR 141.68 Timing Mechanic, and the 500k CIF Ontario Furniture Worked Example

It is Friday morning, August 21 2026. T-minus 1 to the Section 338 Canada cliff. At 12:01 AM Eastern Daylight Time on Saturday August 22, the 50 percent additional ad valorem duty attaches under Chapter 99 headings 9903.03.12 (alcoholic beverages, Ch 22), 9903.03.13 (dairy, Ch 04), and 9903.03.14 (motor vehicles Ch 8703 plus Annex II wood and consumer scope) per U.S. Note 51 to Chapter 99 Subchapter III. Source: hts.usitc.gov, whitehouse.gov/presidential-actions/2026/07/proclamation-11046-alcoholic-beverages, whitehouse.gov/presidential-actions/2026/08/temporary-suspension-of-additional-duties-to-offset-canadian-discrimination.

For a broker sitting on Ontario or Quebec cargo tonight, the operative regulation is 19 CFR 141.68, "Time of entry." Not the arrival timestamp on the pro forma. Not the pier release. The regulation defines when the entry is deemed made for duty-rate purposes, and it maps to the ACE (Automated Commercial Environment) transaction-timestamp architecture in ways that most importers do not fully appreciate until a cliff event forces the question.

Tonight, that question controls whether a 500,000 CIF Ontario furniture container clears at MFN base plus roughly 634 in MPF, or at MFN base plus 250,000 plus MPF. A quarter-million-dollar duty delta pivots on a 3461 timestamp vs a Summary Acceptance timestamp.

19 CFR 141.68 in plain text

19 CFR 141.68 sets four alternative time-of-entry triggers, in a defined priority order. The full text is at ecfr.gov/current/title-19/chapter-I/part-141/subpart-G/section-141.68.

Paragraph (a): For merchandise not released under immediate delivery, the time of entry is the time the entry documentation (CBP Form 3461 or its electronic equivalent transmitted through ACE) is filed, if merchandise has already arrived within the port limits. If the merchandise has not yet arrived, the time of entry is the time of arrival within port limits, provided the entry documentation is already on file.

Paragraph (b): For merchandise released under immediate delivery under 19 CFR 142.21 through 142.29, the time of entry is the time the entry summary (CBP Form 7501 or its electronic equivalent) is filed in proper form with estimated duties attached.

Paragraph (c): The importer may elect to have the time of entry be the time the entry summary is filed with estimated duties attached, at the importer's option, if the entry summary is filed before merchandise arrives within port limits. This is the Deferred Summary election.

Paragraph (d): For merchandise released under a special permit for immediate delivery under 19 CFR 142.21(e), the time of entry is when the entry summary is filed.

Layered on top: 19 CFR 141.69 sets the rate applicable. The rate in effect at the time of entry as defined in 141.68 controls. Not the rate in effect at time of importation into U.S. territory (that is a different rule that applies only where 141.68 does not resolve). Not the rate at release. The 141.68 time-of-entry instant is the rate-lock instant.

ACE transaction architecture, or where the timestamps live

ACE captures three distinct timestamps that a broker or IOR needs to track for a cliff event:

• 3461 Transmission Timestamp. When the broker's ABI (Automated Broker Interface) filer transmits the CBP Form 3461 entry/entry summary record to ACE. Recorded to the second, in Eastern Time, on the filer's ABI transmission log and mirrored on the ACE portal under Entry Summary Query.
• ACE Summary Acceptance Timestamp. When ACE validates the 3461 record against the CBP edit rules, resolves any error codes, and marks the entry as Accepted for release. This can be seconds after transmission on a clean entry, or hours later if error codes trigger broker re-transmission. Historical baseline is 2 to 6 hours for a first-attempt clean entry during business hours, but the queue lengthens on holiday eves and cliff eves.
• Release Timestamp. When CBP or a Customs officer marks the merchandise as released for delivery. This is downstream of Summary Acceptance and does not control the 141.68 time-of-entry instant.

The rate-lock instant per 141.68(a) is the earlier of the entry documentation filing (which most brokers and CBP treat as the 3461 Transmission Timestamp) or the arrival at port limits. But CBP's operational interpretation, reflected in the ACE post-summary correction (PSC) practice under 19 CFR 173.4, is that the entry is deemed "filed in proper form" only once ACE has issued a Summary Acceptance. A rejected 3461 that gets re-transmitted after edit-code fixes uses the re-transmission timestamp, not the original attempt.

This is the operational gap. A broker who transmits a clean 3461 at 11:45 PM EDT August 21 for a truck at the Detroit-Windsor bridge may see ACE Summary Acceptance land at 1:15 AM EDT August 22, on the wrong side of the cliff. CBP could argue the entry was not "filed in proper form" until 1:15 AM, and 9903.03.14 attaches.

Why the ACE queue lengthens on cliff eve

ACE's edit-rule engine processes filings in a first-in-first-out priority queue with capacity controls. On a normal business day the throughput easily absorbs the filing volume with sub-minute Acceptance latency. On a cliff eve (Section 232 aluminum midnight cutovers in 2018, Section 301 List 4A midnight cutovers in 2019, Section 122 sunset July 24 2026), broker filing volume compresses into the final 4 to 8 hours before the instant. Historical CSMS messaging from prior cliffs (CSMS 43831329 for the September 2019 List 4A cutover, CSMS 45419574 for the January 2022 Section 232 aluminum quota reset) documents Acceptance latency spikes from sub-minute to 6-plus hours during the pre-cliff surge window.

Tonight, expect the same. Ontario and Quebec origin cargo at northern-border truck crossings, at Great Lakes rail interchanges, and at east coast ports where Halifax rail-fed traffic drops, all compresses filing into Friday evening. Broker capacity gets stress-tested. CBP has not published a CSMS as of this morning warning of the queue lag, but the pattern is established.

Defensive move: Immediate Transmission election

The broker's defensive counter is to file 3461 records under Immediate Transmission ahead of any operational readiness pretext. Get the 3461 in the ACE queue at 6:00 PM EDT August 21 rather than 11:45 PM EDT. Give ACE 6 hours of queue buffer. If Acceptance lands by 10:00 PM, the pre-cliff rate is defensively locked.

This requires a broker-side workflow change. Many customs brokers hold 3461 transmission for a truck until the driver hands over the entry paperwork at the border commercial parking lot, which is often 15 to 45 minutes before the actual crossing. That is the operational default, not a regulatory requirement. On a cliff eve, the broker should elect Immediate Transmission as soon as the ABI record is data-complete, even if the driver has not yet arrived at the border.

The trade-off: an Immediate Transmission that is later cancelled (because the truck breaks down, or the driver reroutes) requires a CBP Form 7501 amendment or a full entry cancellation under 19 CFR 141.4(c). Broker administrative overhead. On a cliff eve, that overhead is the cheaper side of the trade.

Worked example: 500,000 CIF Ontario furniture container

Ontario-origin case goods (kitchen cabinetry) classified under HTS 9403.40.90 (wooden furniture of a kind used in the kitchen). CIF value at U.S. port of entry, 500,000. USMCA-qualifying under Chapter 4 of the USMCA Uniform Regulations with a full Certificate of Origin. MFN rate on 9403.40.90.80: free. Section 338 Annex II wood scope catches this line under 9903.03.14 per U.S. Note 51 Subchapter III. Fifty percent additional ad valorem on the 500,000 CIF value = 250,000.

Delivery mode: 40-foot container by rail from Ontario to Chicago interchange, then truck to a Nashville distribution center. Cargo departed the Ontario factory August 17. In-transit ETA at Chicago interchange late Friday August 21 evening, with 3461 filing planned by the customs broker at the interchange operator's contract broker desk.

Scenario A: broker files 3461 at 11:30 PM EDT August 21. ACE Summary Acceptance lands at 12:47 AM EDT August 22. Under CBP's operational interpretation, the entry is filed in proper form at 12:47 AM. Rate at time of entry per 141.68(a) = 12:47 AM EDT August 22. 9903.03.14 attaches. Section 338 duty: 250,000. MPF: 634.62 (2026 cap on ad valorem MPF for formal entries above the merchandise-value threshold). Total federal cost added: 250,634.62.

Scenario B: broker elects Immediate Transmission and files 3461 at 6:15 PM EDT August 21. ACE Summary Acceptance lands at 8:22 PM EDT August 21. Entry filed in proper form at 8:22 PM. Rate at time of entry per 141.68(a) = 8:22 PM EDT August 21. 9903.03.14 does not attach (pre-cliff). USMCA-qualifying, MFN free. MPF: 634.62. Total federal cost added: 634.62.

Delta: 250,000. On a 500,000 CIF container. Preserved by a broker workflow change and a 5-hour early transmission.

Scenario C: broker files 3461 at 11:30 PM EDT August 21 but the transmission is rejected with an ACE edit code (e.g., missing NAFTA/USMCA data element per CATAIR message-set). Broker corrects and re-transmits at 12:04 AM August 22. Re-transmission timestamp controls. Entry filed in proper form at 12:04 AM EDT August 22, post-cliff. 9903.03.14 attaches. Duty: 250,000.

The Scenario C risk is why the broker should also run the ABI record through the internal ACE edit-check validation before Friday-evening transmission. Catching a missing element at 4:00 PM Friday is fixable. Catching it at 11:45 PM is a cliff-loss event.

19 CFR 174 protest posture if the rate flips

If Scenario A or Scenario C plays out and the entry lands at 250,000 Section 338 duty, the importer's post-cliff protest under 19 CFR Part 174 needs specific evidentiary anchors. See the 1520(d) vs 174 protest decision tree post-S338 for the full pathway comparison.

The 174 protest must be filed within 180 days of the liquidation date (19 CFR 174.12(e)). The core argument to raise: the 3461 transmission timestamp preceded the 12:01 AM EDT August 22 instant, and the ACE queue lag was operational latency outside the broker's control. CBP's operational interpretation that the entry is "filed in proper form" only at Summary Acceptance is not written into 141.68 itself. The regulation refers to the time entry documentation is filed. Filing is the act of the broker submitting the record to ACE, not ACE's act of validating it.

Evidence to preserve for the protest file:

• ABI transmission log entry with second-level timestamp of the 3461 record.
• ACE Entry Summary Query screenshot showing the transmission timestamp.
• ACE error-code history if any rejections and re-transmissions occurred.
• ACE Summary Acceptance timestamp.
• CSMS messages published between August 19 and the liquidation date documenting known ACE queue lag conditions on August 21 evening.
• Broker's operational log noting Immediate Transmission election if that was the workflow.

CBP's response posture is not tested for Section 338 Canada yet because the July 20 2026 Proclamations are the first Section 338 invocation in modern trade practice. The CIT (Court of International Trade) precedent on 141.68 is sparse. Zenith Radio Corp v. United States 437 US 443 (1978) is the closest doctrinal anchor, but it addresses rate-at-importation for a different regulatory context. Broker and importer counsel should treat the 174 protest as legitimately contestable, not a losing proposition.

Cross-references

For the FTZ election alternative that locks the pre-cliff rate at admission rather than at entry, see Form 214 Privileged Foreign election mechanics. For the 3-day suspension proclamation background, see Section 338 Canada 3-day suspension proclamation T-2 reset. For the bonded warehouse fallback under 19 CFR 19, see Class III bonded warehouse Section 338 Canada fallback.

Bottom line for tonight

Brokers filing Ontario, Quebec, or any Canadian-origin cargo tonight for entries expected to release August 21 or early August 22 should elect Immediate Transmission on 3461 as soon as the ABI record is data-complete. Do not hold transmission until the driver hits the border commercial lot. Do not hold transmission until the ship berth confirms. Get the record into the ACE queue with a 4-plus hour buffer to Summary Acceptance. If ACE Acceptance lands pre-cliff, the rate is locked at MFN base. If it lands post-cliff, preserve the transmission-timestamp evidence for a 174 protest.

A 500,000 CIF Ontario furniture container carries a 250,000 duty delta on the wrong side of the timestamp. That delta is the cost of a broker workflow default that was fine for every non-cliff Friday evening this year but that stops being fine at 6:00 PM EDT August 21 2026.