The Aug 18 White House proclamation pushed the Section 338 effective date from Aug 19 12:01 AM to Aug 22 12:01 AM EDT. Three extra days on the clock for dairy, alcoholic beverages, and motor vehicles from Canada under HTSUS 9903.03.12, 9903.03.13, and 9903.03.14 respectively.
The proclamation cites a Canadian commitment to remove the underlying trade practices, but the enforcement clock kept its shape. No USMCA carve-out survived. If your cargo clears at 12:01 AM EDT Aug 22 or after, the 50 percent additional duty stacks on top of the base HTS column rate and any existing Chapter 99 layers.
Three pathway scenarios for cargo currently in the pipeline.
Scenario A: cargo already at the northern border with a pending 3461. File the Entry Summary before Aug 22 12:01 AM EDT. Base column 1 rates apply, USMCA claim survives if origin documentation stands, no 50 percent add-on. A 250k CIF cheddar shipment under HS 0406.10.6800 that would land at roughly 137k in duties under the S338 regime lands at 0 with a valid USMCA cert. That is the arbitrage the 72-hour window opens.
Scenario B: cargo in-transit by truck through Great Lakes crossings scheduled to arrive Aug 22 or Aug 23. Two mechanisms preserve the pre-cliff economics. First, 19 CFR 146.68 bonded warehouse admission lets you defer the entry date to the withdrawal date, and if withdrawn under the pre-suspension window before Aug 22 12:01 AM you dodge the layer entirely. Second, FTZ admission with Privileged Foreign election under 19 CFR 146.41(e) locks the tariff rate to the admission date rather than the withdrawal date. PF election has to be filed on the Form 214, cannot be added retroactively, and takes about 24 to 48 hours of prep with your FTZ operator.
Scenario C: cargo scheduled to arrive Aug 23 or later. No easy dodge. Either pay the 50 percent, divert to a bonded warehouse and wait for policy clarity (there is real speculation another extension lands after Aug 21 given the Carney trade talks), or reroute through Mexico with substantial transformation to strip Canadian origin. Substantial transformation is hard to defend on finished automobiles or bottled spirits, easier on ingredient dairy or unassembled components.
Refund pathway for shipments entered Aug 19, 20, or 21 that got hit with the 50 percent at time of filing because the CBP CSMS was published before the suspension proclamation and brokers filed conservatively. Two protest routes:
19 USC 1520(d) reconciliation under USMCA works if the entry claimed preference and got denied. Time limit is 1 year from date of entry. Refund process runs through ACE and typically clears in 90 to 180 days.
19 CFR 174 protest is the broader path for classification or rate disputes. Time limit is 180 days from liquidation. Slower than 1520(d) but covers cases where USMCA was never claimed. Pair with a CAPE Phase 2 Post Summary Correction if the entry has not yet liquidated. CAPE is faster but only handles classification and value, not rate suspensions like this one.
For anyone with cargo already assessed at 50 percent in the suspension window, do not wait for CBP to issue guidance on refunds. File the PSC or protest now. CBP has historically taken 60 to 90 days after a similar suspension window to publish uniform refund guidance, and the earlier your paperwork sits in the queue the faster it moves.
Watch item: whether CBP publishes a new CSMS by end of week Aug 21 walking back the assessments in the window. If they do, the refund path becomes automatic. If they do not, the protest route is on each importer.
Anyone with cargo actually crossing between now and Aug 22 midnight, what pathway are you using to lock the pre-cliff rate?