Congratulations – your small business is officially successful enough that you need a big truck to haul your product across the country. But once you've got that truck sorted out, there's a good chance you'll need a United States Department of Transportation number, also known as a USDOT or DOT number.

A DOT number gives your company a unique identifier, which helps authorities quickly access your information in the unfortunate event of an accident, or during more routine tasks like compliance reviews. As a general rule, you'll need a DOT number if you have a commercial vehicle that hauls passengers or goods across state lines, but the application process is mercifully painless.

Is a DOT Number Necessary?

According to the Federal Motor Carrier Safety Administration or FMCSA, "companies that operate commercial vehicles transporting passengers or hauling cargo in interstate commerce must be registered with the FMCSA and must have a USDOT Number." Sounds pretty cut and dried, but it gets just a little more complex than that.

You know you need a DOT number if your vehicle meets at least one of these descriptions, and is involved in interstate trade, traffic or transport in the U.S.:

  • Your company's business vehicle has a gross combination weight aka gross combination weight rating or a gross vehicle weight of 10,001 pounds or more.
  • The vehicle is designed to transport eight or more passengers for compensation, which includes the driver.
  • The vehicle is designed to transport 15 or more not-for-compensation passengers, which includes the driver. 
  • If your commercial vehicle is used to transport any sort of hazardous material that requires a safety permit for intrastate commerce.

Interstate trade, traffic or transport in the U.S. refers to:

  • Between a place in a state and a place outside of such state, including a place outside of the U.S.
  • Between two places in a state through another state or a place outside of the U.S.
  • Between two places in a state as part of trade, traffic or transportation originating or terminating outside the state or the U.S.

The Application: DOT Requirements

You can apply for a DOT number at the FMCSA's official website, which is as easy as filling in the blank fields and hitting "Submit." Before you get started, be sure to have your basic company contact info, the license status of your drivers, the type and number of vehicles in your fleet and your HAZMAT qualifications on hand. You'll also need info about your vehicle's operation and cargo classifications.

Application forms are never fun, but here's some good news for your business – applying for a USDOT number is free, although you will need to provide a credit card number for verification purposes. To forgo the credit card requirement, which serves as a digital signature, you can also opt to download forms MCS-150, MCS-150B and MCS-150C from the FMCSA's site and mail in the hard copies to their headquarters in Washington, DC. Unless there's a problem with your application, online registration is usually processed instantly, while it takes about four-to-six weeks to process your DOT number via mail.

Connecting More DOTs

Once you get a DOT number, it must be displayed on every single vehicle in your commercial fleet, on both sides of its engine and in a contrasting color that is easily visible from a distance of 50 feet.

In addition to getting a DOT number, it's your driver's responsibility to know and comply with any applicable standards laid out by the FMCSR, meaning Federal Motor Carrier Safety Regulations. The FMCSA offers these guidelines as a free PDF on their official website.

Only 31 states have laws on the books agreeing to enforce DOT number regulations, but it's still a regulation at the federal level, so don't think you're off the hook just because you live in South Dakota or Tennessee; noncompliance can result in hefty fines, not to mention used as potent lawsuit fodder. If you want to dig even deeper into DOT numbers, the full breadth of the regulations is detailed in section 49 of the Code of Federal Regulations or CFR 385.403.