ACE Maintenance Windows and Entry Type 13 Mail Test: Oct 2026

Key Points

• ACE will undergo invasive maintenance on Thursday, October 8, 2026, from 5:00 a.m. to 7:00 a.m. ET, during which response-notification delays are expected.
• A second ACE invasive maintenance window runs from Saturday, October 10, 2026 at 10:00 p.m. ET through Sunday, October 11, 2026 at 4:00 a.m. ET.
• CBP held a Post-Deployment Support Call on October 7, 2026 covering the newly implemented Entry Type 13 (ET 13) test for ACE processing of international mail shipments (INT-057 and CBP-290).
• Both maintenance periods are classified as "standard invasive," meaning ACE production systems may be intermittently unavailable or degraded, not merely slow.

On this page

1. What CBP announced
2. ACE maintenance window details
3. Entry Type 13 international mail test
4. What importers, brokers, and filers should do
5. Key references

CBP issued three CSMS notices on October 7, 2026, covering two upcoming ACE production maintenance outages and a post-deployment support call for the new Entry Type 13 international mail processing test. Filers with transmissions or status checks scheduled during either maintenance window should plan accordingly. The links in this article go to the primary CBP CSMS bulletins themselves. Read the source.

What CBP announced

All three notices came through CBP's Cargo Systems Messaging Service (CSMS) on October 7, 2026. Two address planned ACE production downtime; one addresses operational support for a recently deployed ACE feature affecting international mail entries.

ACE maintenance window details

Window 1 (CSMS 70145514): ACE production will undergo standard invasive maintenance on Thursday, October 8, 2026, from 5:00 a.m. to 7:00 a.m. ET. CBP specifically warns that filers may experience delays in receiving response notifications during this two-hour period. Because the maintenance is classified as invasive, the production environment, not just a secondary system, is affected.

Window 2 (CSMS 70143921): A second invasive maintenance period is scheduled to begin on Saturday, October 10, 2026 at 10:00 p.m. ET and run through Sunday, October 11, 2026 at 4:00 a.m. ET, a six-hour window. No specific warning about response notifications was included in this notice, but the invasive classification applies equally.

Taken together, filers face two separate disruption periods across a single week. Anyone relying on ACE for time-sensitive entry submissions, status pulls, or automated partner-government agency (PGA) message sets should build contingency time into their workflows before each window opens.

Entry Type 13 international mail test

Separate from the maintenance notices, CBP reminded trade participants on October 7, 2026 of a Post-Deployment Support Call (CSMS 70137892) covering two ACE enhancements:

• INT-057: Implementation of Entry Type 13 (ET 13) Test in ACE for U.S. Mail Processing.
• CBP-290: Mail Entry Type 13 Test.

Entry Type 13 is a new entry classification within ACE designed specifically for processing international mail shipments. The post-deployment support call format indicates these enhancements have already been pushed to production; the October 7 call gave the trade community a structured opportunity to surface implementation issues directly with CBP technical staff. Brokers and mail-facility operators who process international mail entries should confirm their ACE configurations and internal workflows align with the ET 13 requirements now that the deployment is live.

What importers, brokers, and filers should do

• Avoid scheduling critical ACE transmissions or status checks between 5:00 a.m. and 7:00 a.m. ET on October 8 and between 10:00 p.m. October 10 and 4:00 a.m. October 11; submit entries before each window opens or after it closes.
• Review the CSMS 70137892 bulletin and any posted materials from the October 7 post-deployment call to confirm your ACE filing setup is compatible with the live Entry Type 13 (ET 13) enhancements for international mail (INT-057 / CBP-290).
• Monitor the CBP CSMS page for any follow-up notices if either maintenance window is extended or if additional ET 13 guidance is released.

Key references

• CSMS 70145514: ACE invasive maintenance, October 8, 2026, 5:00 a.m. to 7:00 a.m. ET.
• CSMS 70143921: ACE invasive maintenance, October 10-11, 2026, 10:00 p.m. to 4:00 a.m. ET.
• CSMS 70137892: Post-deployment support call for Entry Type 13 ACE mail processing (INT-057 and CBP-290), October 7, 2026.