What This Guide Covers
What 49 CFR Part 396 requires for periodic inspection and ongoing maintenance recordkeeping, and how those requirements attach to each individual power unit or trailer — not the fleet as a whole.
How This Area Fits Your Operation
Every vehicle in a combination (a tractor and each trailer separately) must pass its own periodic inspection at least once every 12 months, measured from the last day of the month the inspection was performed — not a flat 365-day count, and not a single inspection covering the whole combination. Separately, every carrier must systematically inspect, repair and maintain each vehicle under its control, with parts and accessories kept in safe operating condition at all times. When a roadside inspection turns up a defect, the carrier generally has a limited window — around 15 days — to certify that violations were corrected, though the correction of an out-of-service defect itself happens much sooner, typically before the vehicle is driven again.
Records To Organize
- Periodic (annual) inspection documentation for each power unit and trailer
- Maintenance and repair records for each vehicle
- Driver vehicle inspection reports and their certification of repair
- Vehicle registration, IRP cab card and applicable state permits
- Roadside inspection reports, where issued
- Source49 CFR 396.3 — Inspection, Repair, and Maintenance — eCFR· Federal · checked 2026-09-16
Dates That May Require Attention
- Periodic inspection due 12 months from the last day of the month of the prior passing inspection (49 CFR 396.17)
- Roadside inspection report certification, generally within about 15 days of the inspection
- Maintenance records retained for 1 year while the vehicle is in the carrier's control, plus 6 months after it leaves (49 CFR 396.3)
- Source49 CFR 396.17 — Periodic Inspection — eCFR· Federal · checked 2026-09-16
How DOT Serenity Fits
DOT Serenity connects each vehicle to its own records and calculates the next periodic-inspection and maintenance-due dates directly from your recorded service history — never an assumed or estimated date.