When is my MCS-150 due?
MCS-150 is filed every two years on a schedule keyed to the last digit of the USDOT number. The deadline is the last day of the month indicated by the next-to-last digit; the month maps from a published FMCSA table. Carriers also file MCS-150 within 30 days of any material change (name, address, vehicles, mileage).
The biennial schedule pairs the next-to-last digit of the USDOT (1-9, then 0 = month 10) with a calendar month. A USDOT ending in -X3 files in March; -X7 files in July; -X0 files in October. The last digit (the right-most) determines whether you file in odd or even years (odd last digit = odd years, even = even years).
Example: USDOT 1234567 — last digit 7 (odd years) and second-to-last 6 (June). So this carrier files MCS-150 every odd year, due June 30.
Beyond the biennial cycle, MCS-150 is required within 30 days of any material change: legal-name change, business-address change, change in number of vehicles or drivers, change in commodities hauled, or change in operation type (interstate vs intrastate, hazmat status).
Missing the biennial deadline triggers FMCSA to deactivate the USDOT — the carrier loses interstate operating authority until MCS-150 is filed. There is no late fee, but the deactivation has to be cured before the next interstate trip.