From the FMCSA.
Consolidation of USDOT PIN and MC/MX Docket PIN The Federal Motor Carrier Safety Administration (FMCSA) Office of Registration will soon consolidate the USDOT, MC and MX Personal Identification Numbers (PINs) into one USDOT PIN. This system deployment effort will eliminate the need for multiple, MC and MX PINs.
All carriers and other FMCSA regulated entities will be impacted. After deployment, customers will only need a USDOT PIN to access FMCSA systems. If an alternate PIN (e.g., MC) is used, the system will notify that the information does not match the record on file and they will be prompted with a link to reset or request a USDOT PIN.
Expect to see the change in FMCSA systems beginning April 27. When deployed, you will only be able to use its USDOT PIN to access FMCSA systems, submit changes and request updates to its US DOT and operating authority records. Updates can be done online via the FMCSA online registration system or by selecting the “FMCSA Registration and Updates” link under FMCSA Services from the SAFER website.
Click here if you do not have your USDOT PIN or need to reset it.
For more information, visit the FMCSA registration Frequently Asked Questions site.