Is MCS-150 the same as UCR?
No. MCS-150 is FMCSA biennial registration; UCR (Unified Carrier Registration) is a separate annual-fee program collected by participating states under 49 USC §14504a. Both apply to most interstate carriers, but they are different filings with different agencies and different fee structures.
MCS-150 updates the FMCSA carrier record under 49 CFR §390.19. There is no fee. The form runs on a 24-month cycle keyed to the USDOT number.
UCR is a state-administered fee program. The carrier pays a single annual fee based on fleet size; the fees fund participating-state motor-carrier safety programs. Fees range from about $46 (1-2 vehicles) up to about $44,000 (1,001+ vehicles) per year. UCR is filed in the carrier's base state and the registration is honored in every UCR-participating state.
Both apply to most interstate carriers. A new owner-operator typically files: USDOT (free), MCS-150 (free), MC if for-hire ($300), BOC-3 ($75), UCR ($46-$76 first year), HVUT 2290 ($550 + $39 service), and IRP/IFTA (state-by-state). MCS-150 and UCR are two of those line items, not one.
Practical confusion: state DMVs sometimes refer to "the federal registration" loosely without distinguishing MCS-150 from UCR. They are separate programs administered by different bodies — FMCSA for MCS-150, the UCR national board (with state collection) for UCR.