# Common MCS-150 Filing Mistakes and How to Avoid Them

Canonical: https://www.fastmcs150filing.com/guides/common-mcs-150-mistakes
Category: FMCSA Compliance
Published: 2026-04-24
Updated: 2026-04-24
Read time: 6 min read

> The most common MCS-150 errors: wrong fleet counts, cargo miscategorization, naming the wrong safety representative, and missed deadlines. Here is how to avoid each.

## TL;DR

> The most common MCS-150 errors — wrong fleet counts, miscategorized cargo, the wrong safety representative, round-number mileage, missed deadlines — are quiet ones that distort your FMCSA record and inflate CSA scores for two years.

## Key takeaways

- Fleet counts feed Safety Measurement System normalization — double-counted leased units distort CSA scoring.
- Mileage is cross-checked against IFTA quarterly returns; obvious round numbers like 100,000 read as placeholders.
- The Designated Safety Employee/Representative must actively manage compliance and be reachable during a new-entrant audit.
- Legal name on MCS-150 must match FMCSA authority records exactly — including suffix formatting like LLC vs L.L.C.

## FAQ

### What is the most common MCS-150 filing mistake?

Wrong fleet size — either double-counting leased equipment, counting trailers as power units, or estimating from memory instead of pulling an actual inventory. Fleet numbers feed into the FMCSA's Safety Measurement System, so a wrong count can skew your CSA scores for the next two years.

### How should I estimate annual mileage on MCS-150?

Use actual numbers when you have them — odometer readings, ELD exports, or IFTA-reported miles. If you have to estimate, base it on real averages per truck rather than a round number. The FMCSA cross-references MCS-150 mileage against roadside inspection and IFTA data and will flag wildly inconsistent figures.

### Who should I list as the safety contact on MCS-150?

The person who actively manages regulatory compliance at your company. For an owner-operator, that is you. For a small fleet, it is typically the safety manager or operations lead. Do not list an outside consultant, attorney, or accountant unless they are contracted as your designated compliance officer.

### Can I fix a mistake on my MCS-150 after submitting?

Yes. You can file a corrective MCS-150 at any time through the URS portal — the most recent filing supersedes the prior one. The sooner you correct it, the less exposure you have if an audit references stale data.

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