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Comparison

DOT number vs MC number vs MX number

Short answer

USDOT is the FMCSA carrier-existence identifier under 49 CFR §390.19T, required for any motor carrier subject to FMCSA jurisdiction (commercial vehicles 10,001 lbs GVW or more crossing state lines, hazmat in placarded quantities, or 9-15 passenger non-business vehicles). MC is the FMCSA operating authority under 49 USC §13902, required for for-hire interstate motor carriers (US-domiciled or Canadian) and costing $300 per authority type per §13908. MX is the cross-border operating authority under 49 CFR §365.501, required for Mexican-domiciled long-haul carriers operating into the US under the NAFTA/USMCA cross-border program. Different scopes, different applications, all three coexist in the FMCSA system: a single carrier might hold a USDOT only (private), USDOT plus MC (US for-hire), or USDOT plus MX (Mexican). The MX program runs through a separate provisional authority phase under FMCSA's Compliance & Enforcement office before full operating authority.

Reviewed by Korey Sharp-Paar · Updated

Side-by-side comparison

DimensionUSDOTMC / MX
Authority49 CFR §390.19TMC: 49 USC §13902. MX: 49 CFR §365.501
FunctionCarrier identifierMC: For-hire operating authority. MX: Mexican cross-border authority
Applies toAny FMCSA-regulated carrierMC: For-hire US/Canadian carriers. MX: Mexican long-haul carriers
Application formMotus registration (URS before May 2026)MC: OP-1. MX: OP-1MX
BIPD insuranceNot required for DOT aloneMC and MX: $750k-$5M (§387.9)
BOC-3Not required for DOT aloneMC and MX: Required
Processing timeIssued through Motus registrationMC: FMCSA controls the timing. MX: FMCSA controls the timing (adds cross-border vetting)

When DOT alone is enough

A USDOT number alone is sufficient for two main carrier categories: (1) private motor carriers - companies that move their own freight in their own equipment without offering transportation services for compensation, and (2) intrastate-only carriers operating under state authority that doesn't require federal MC. Both categories are subject to §390 carrier-identification rules and must register a USDOT, but neither falls under §13902 for-hire operating authority.

Private fleets are common at large retailers, manufacturers, and oil-and-gas producers - companies whose primary business is not transportation but who operate their own freight equipment as part of their core operations. Walmart's private fleet, Frito-Lay's distribution, ExxonMobil's tanker fleet - all are private carriers that need USDOT but don't need MC because they don't haul for compensation.

When MC is required

MC is required for any for-hire interstate motor carrier - a company that physically transports freight or passengers for compensation across state lines. The §13902 operating authority is the federal license that lets the carrier accept compensation for transportation services in interstate commerce. FMCSA controls how long MC review takes, and the grant also depends on the BOC-3 + BMC-91 filing for the federal-level qualification gates.

For a typical owner-operator running interstate freight, the path is: register to get the USDOT, apply for the MC, file BOC-3 with a registered process-agent provider, file BMC-91 with an insurance provider for §387.9 BIPD, and wait out FMCSA processing. FMCSA controls the timing. Authority is granted once the BOC-3 and insurance are on file and the 10-day protest period after the application's FMCSA Register notice has passed (49 CFR 365.203T).

What the "MC/MX number" on forms means

FMCSA assigns operating-authority docket numbers from a single numbering space and distinguishes the carrier type by prefix: MC for US- and Canadian-domiciled for-hire carriers, MX for Mexican-domiciled carriers, and FF for freight forwarders. Because any one carrier holds only one of those prefixes, FMCSA systems print a combined field rather than three separate ones - the SAFER company snapshot shows "MC/MX/FF Number(s)", and insurance filings (BMC-91, BMC-84) and UCR registration screens ask for an "MC/MX number".

So an MC/MX number is not a separate credential you apply for. It is whichever operating-authority docket number your company holds: a US owner-operator with active for-hire authority enters the MC number, a Mexican-domiciled cross-border carrier enters the MX number, and a private fleet operating on a USDOT number alone has no MC/MX number to enter - that field stays blank or reads N/A. If a form rejects a blank MC/MX field, it is a for-hire-only form and does not apply to private carriage.

When MX applies

MX is the Mexican cross-border long-haul authority under §365.501. Mexican-domiciled carriers operating into the US - typically running freight from Mexican origin to US destination, or vice versa - file Form OP-1MX and receive an MX number. The MX is functionally equivalent to an MC for FMCSA jurisdiction purposes (same §387 financial responsibility, same §366 process agent requirements), but the application path goes through the FMCSA Mexico Office and adds cross-border verification.

US-domiciled carriers operating across the Mexican border do not need MX - they operate under their US MC. Canadian-domiciled carriers operating across the US-Canada border also use MC (not MX) because §365.501 is Mexico-specific. The MX number is reserved for the specific Mexican-domiciled long-haul use case.

How the three identifiers interact

All three identifiers coexist in the FMCSA system. Most carriers hold a single USDOT plus, depending on operations, an MC or an MX (rarely both). The USDOT is the foundational carrier identifier; MC and MX are operating-authority overlays that build on top of an active USDOT. In FMCSA's records (Motus public search), the USDOT number is the primary identifier, with the MC or MX as a linked authority record.

Brokers and shippers look a new carrier up by USDOT number or company name in FMCSA's Motus public search. The §387.9 insurance and §366.4T process-agent filings on the authority are what gate the carrier's legal authority to accept compensation for transportation services. The USDOT alone doesn't establish for-hire authority.

Frequently asked questions

Can a single carrier have all three numbers?

Theoretically yes for a US-domiciled carrier with Mexican operations and Canadian cross-border operations, but in practice almost no single legal entity holds DOT + MC + MX simultaneously. The pattern is separate corporate entities for each jurisdiction (US LLC with DOT + MC, Mexican S.A. de C.V. with MX) operating under shared management.

Does a private fleet need any of these?

A private US-domiciled fleet (carrier moving its own freight) needs a USDOT number under §390.19T but does not need an MC because §13902 operating authority only applies to for-hire carriage. Private intrastate carriers may operate under state-only authority depending on state law.

How long does each take to issue?

FMCSA controls the timing for all three. The USDOT number is issued through the Motus registration. MC authority is granted once the BOC-3 and insurance are on file and the 10-day protest period after the application's FMCSA Register notice has passed (49 CFR 365.203T). MX applications add cross-border verification by FMCSA.

What is an MC/MX number?

MC/MX is not a separate credential - it is the combined label FMCSA systems use for the operating-authority docket number, whichever prefix applies. FMCSA assigns docket numbers from one numbering space with an MC prefix (US or Canadian for-hire carriers), MX prefix (Mexican-domiciled carriers), or FF prefix (freight forwarders), so SAFER, insurance filings, and UCR screens print one "MC/MX/FF Number" field. Enter your MC number there if you hold US/Canadian for-hire authority, your MX number if you are a Mexican-domiciled carrier, and leave it blank if you operate under a USDOT number only.

Related comparisons

Get DOT and MC together

Your USDOT registration and MC application are prepared together. FMCSA controls the timing of the grant. We prepare your USDOT number and MC operating-authority application; it is submitted to FMCSA in Motus by you or a filer you authorize. FMCSA charges a $300 application fee for each operating authority type (49 CFR 360.3T); a USDOT number is free. Our $199 service fee and the $300 FMCSA fee are itemized as two separate amounts before you pay ($499 total).

Start your application — $199 service fee + $300 FMCSA fee MC authority overview

Submitted to FMCSA in Motus by you or a filer you authorize.

Independent filing service operated by Fast Filing Group LLC. Not affiliated with FMCSA, USDOT or any government agency.

This page is informational and is not legal advice. Verify regulatory requirements against the current text of 49 CFR Parts 365, 387, and 390 before relying on this comparison.

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