When is MCS-150 due?
Every 24 months on a schedule keyed to the carrier's USDOT number. The last digit determines the month, and the 2nd-to-last digit determines whether the deadline falls in an even or odd year. The biennial filing applies whether or not the carrier's data changed since last update.
FMCSA mandates the biennial MCS-150 update under 49 CFR §390.19T(b)(2)–(3). The exact month is set by the last digit of the USDOT (1=January, 2=February, …, 9=September, 0=October), and the year is set by the 2nd-to-last digit (odd = odd year, even = even year). A carrier with USDOT 1234567 (last digit = 7, 2nd-to-last digit = 6) updates in July of every even year.
The biennial filing is required even if no data changed. FMCSA uses the filing as a "yes, the carrier still exists" signal - skipping it triggers USDOT deactivation in the SAFER public snapshot, which most freight brokers and shippers check before tendering loads.
On top of the biennial cycle, MCS-150 must be re-filed within 30 days of any material data change: new operating address, new contact information, new operating classification, new vehicle count, or new driver count. The 30-day rule in FMCSA registration guidance is independent of the biennial schedule.
Filing late or missing the biennial update lands the carrier in "Inactive" status. Reactivation requires a fresh MCS-150 plus typically a 24-48-hour SAFER refresh. There is no FMCSA late fee for an inactive-status reactivation, but the lost weeks of out-of-service status can cost real revenue.