Do I need a new MCS-150 after a business name change?
Yes. A change to legal business name (LLC reformation, sole-prop to LLC, DBA add, M&A) requires filing MCS-150 within 30 days of the change. The MCS-150 is the FMCSA's record-of-truth for legal name; insurance certificates, BOC-3 designations, and broker onboarding all reference it.
A name change is one of the trigger events for an out-of-cycle MCS-150 filing. The 30-day window starts the day the new legal name is effective at the state — not the day the carrier finds out.
Operationally: after the LLC paperwork is filed at the state, the carrier has 30 days to update FMCSA via MCS-150. If the EIN stayed the same (most LLC reformations), the USDOT carries forward to the new name. If the EIN changed (rare — usually only in M&A), FMCSA treats it as a new entity and a fresh USDOT + MC is required.
Cascade effect: once MCS-150 is updated to the new legal name, every downstream registration that references the legal name has to be refiled too. That includes BOC-3 (re-file with the new name), insurance filings (BMC-91/84/85 with the new named insured), state UCR registration, and IRP plates.
Operating under the old legal name after the LLC change is a §390 violation and creates a tangled audit trail. The 30-day MCS-150 update window is generous; missing it is a frequent audit citation.