When an investigator asks for maintenance records, they are not looking for a stack of invoices. They want a file for each vehicle that shows a system: what the vehicle is, what service is due, and what was done. Part 396 spells out what that file needs.
The Systematic Maintenance Requirement
Under 49 CFR 396.3, every motor carrier must systematically inspect, repair and maintain all motor vehicles subject to its control. That includes trucks, tractors, trailers and converter dollies.
“Systematic” is the key word. You need a plan, not just repairs when something breaks. The records must show that inspections and maintenance happen on a regular schedule.
Parts and accessories must be in safe and proper operating condition at all times, including the equipment covered by Part 393. A good system usually includes preventive maintenance intervals based on miles, engine hours or time, plus a way to track when each service is due and confirm it was completed.
What Each Maintenance File Must Contain
For each vehicle a carrier controls for 30 consecutive days or more, 49 CFR 396.3(b) requires a record that includes:
- Identification of the vehicle, including company number if any, make, serial number, year and tire size
- The owner’s name, if the carrier does not own the vehicle
- A means to indicate the nature and due date of the various inspection and maintenance operations to be performed
- A record of inspection, repairs and maintenance, showing the date and nature of each
- For buses, a record of tests on push-out windows, emergency doors and emergency door marking lights
The file can be paper or electronic. What matters is that it is complete and easy to produce.
Retention Rules
Under 49 CFR 396.3(c), maintenance records must be kept where the vehicle is either housed or maintained for one year, and for six months after the vehicle leaves the carrier’s control.
Other Part 396 records have their own retention periods:
- Driver vehicle inspection reports (DVIRs), with repair certifications: three months, under 49 CFR 396.11
- Annual periodic inspection reports: 14 months, under 49 CFR 396.21
- Roadside inspection reports: under 49 CFR 396.9, the carrier must certify that violations were corrected and return the report within 15 days, and keep a copy for 12 months
- Inspector qualifications under 49 CFR 396.19 and brake inspector qualifications under 49 CFR 396.25: for as long as the person performs that work for you and for one year after
Keeping everything together by unit number makes audits much faster.
Leased Vehicles and Trailers
Leased equipment is where many files fall apart. If you control a leased vehicle for 30 days or more, you need a maintenance file for it, even if the owner does the maintenance. Get copies of the owner’s records and make sure the lease is clear about who maintains the vehicle.
Trailers are the other weak spot. They often sit for long periods or move between customers, and their files get neglected. Treat every trailer like a power unit with its own file, schedule and annual inspection.
Intermodal equipment has additional rules that split responsibilities between the equipment provider and the carrier. If you handle intermodal chassis, check those provisions directly.
Common Gaps and a Maintenance File Checklist
These are the problems investigators find most often:
- No schedule or due dates, only a record of past repairs
- Missing files for leased tractors or trailers
- Vendor invoices that do not identify the unit
- Expired annual inspections, especially on trailers
- DVIRs with defects but no repair certification
- Roadside inspection reports never certified or returned
- Records discarded before the retention period ends
For each truck and trailer, confirm you have:
- Vehicle identification details and owner information
- A written maintenance schedule with due dates
- A dated record of all inspections, repairs and maintenance
- The current annual inspection report and proof of inspection on the unit
- DVIRs and repair certifications for the last three months
- Any roadside inspection reports and certifications from the last 12 months
DOT Compliance Watch keeps maintenance and inspection records organized by vehicle and sends alerts before annual inspections come due. That gives you a single place to see the status of every unit. For questions about your specific equipment or operation, check with FMCSA or a qualified advisor. Our resources page has more guidance.
Build files that tell the story
A good maintenance file shows an investigator that you run a real system. DOT Compliance Watch helps you keep every unit’s records complete and current. Start your free 14-day trial and cancel anytime.