Can I correct an MCS-150 after I submit it?
Yes. The FMCSA Portal lets you file a corrected MCS-150 at any time — there is no separate "amendment" form. The corrected MCS-150 supersedes the prior submission in SAFER on the next refresh cycle (typically 24-48 hours). Corrections to legal name, business address, fleet count, and mileage all run through the same MCS-150 path.
The 49 CFR §390.19 framework requires the carrier to maintain a current MCS-150 at all times. "Current" means accurate — if the prior submission contained an error, the carrier files a corrected MCS-150 to remediate. The FMCSA Portal does not distinguish "corrections" from regular filings; it accepts a fresh MCS-150 and treats it as the new authoritative record. The prior submission is replaced in SAFER on the next refresh.
The most common corrections are typos in legal name (missing comma, wrong suffix), wrong fleet vehicle counts (carrier added or removed trucks since last update), wrong mileage (carrier reported the wrong year's data), and wrong contact information (phone number, email, address change). Each of these is corrected by submitting a fresh MCS-150 through the FMCSA Portal with the accurate data.
Some corrections trigger downstream filings. A legal-name change requires a fresh BOC-3 (the §366.4 process-agent designation is keyed to the legal name). An MC-related update may require coordination with the §387 financial-responsibility filing (BMC-91 references the carrier's legal identifiers). For pure data corrections that don't affect carrier identity, the MCS-150 alone is sufficient.
For carriers caught in serious data errors that affect FMCSA enforcement (wrong mileage that affected SMS scoring, wrong fleet count that affected UCR fees), correcting the MCS-150 retroactively is necessary but not sufficient — the underlying enforcement-affected systems may need separate remediation. Carriers in this situation typically engage with FMCSA directly through the carrier's state Field Office.