Operating Authority
What is an authority? What does it give you the power to do as opposed to just putting your truck on with a company?
This link should be helpful:
Registration & Assistance: USDOT Number/Operating Authority - Federal Motor Carrier Safety Administration
Operating authority is for you as an owner operator (or a company) to operate as a motor carrier in the United States.
Pennsylvania for example also requires that you get authority from the PUC or Pennsylvania Public Utility Commission.
In any case the one I think you are asking about is from the Feds. It used to be an ICC number but now is just referred to as a MC or Motor Carrier number.
They are the numbers that are usually displayed on a trucks door or sleeper.
They must be in contrasting color from the background they are on and be readable from 50 feet.
Some states like NY have size requirements for the letters and other information that must be contained one the side of trucks.
If you getting your authority for the first time and aren't that confident about the reg's there are co's that will handle all of the filing for you for a price.
But if you are good online you can save yourself about $1000.00 by doing it yourself since most filing can be done online.
In short having your own authority will give you permission to go and get your own customers.Having your own authority will also usually make you responsible for all of the other expenses like fuel and plates etc...
Working under somone elses authority will usually give you a break in that they will pick up some of those expenses.
It is tough out there! Be careful in this decision!!!
Hope this helps and good luck