DOT Drug Test: Employer Guide to Rules, Process and Results

A DOT drug test is a urine drug test that follows the U.S. Department of Transportation’s procedures in 49 CFR Part 40. It applies to safety-sensitive transportation employees. It is collected on a federal custody form, tested by an HHS-certified laboratory for five drug classes and reviewed by a Medical Review Officer (MRO) before the employer gets a result.

This guide is for HR and operations staff at employers with DOT-covered employees. It covers when DOT tests are required, how a test moves from collection to MRO review, what to do with each type of result, and how DOT tests differ from company drug tests. For substance-by-substance detection windows, see GoodHire’s 5-panel drug test guide. For the wider set of DOT hiring checks, see the DOT background check overview.

What Is a DOT Drug Test?

A DOT drug test is any drug test that a DOT agency rule requires. Two layers of regulation apply. Part 40 sets the procedures for every DOT test: how specimens are collected, which laboratories may test them, and how results are reviewed and reported. Each DOT agency’s own rule then sets who is covered and when testing happens, such as 49 CFR Part 382 for commercial drivers regulated by the Federal Motor Carrier Safety Administration (FMCSA).

A few roles appear throughout the process:

• Designated employer representative (DER): the employer’s staff member authorized to remove employees from safety-sensitive duties and make required testing decisions.
• Medical Review Officer (MRO): a licensed physician who reviews laboratory results and decides whether a result is verified.
• Substance abuse professional (SAP): a qualified professional who evaluates an employee after a violation and recommends education or treatment and follow-up testing.
• Consortium/third-party administrator (C/TPA): a service agent that can manage parts of an employer’s program, such as random selections.

Who Must Follow DOT Drug Testing Rules?

DOT testing applies to employees in safety-sensitive roles defined by these agencies:

• FMCSA: drivers of commercial motor vehicles who need a commercial driver’s license (CDL)
• Federal Aviation Administration (FAA): safety-sensitive aviation employees, such as flight crew and aircraft maintenance staff
• Federal Railroad Administration (FRA): covered railroad employees
• Federal Transit Administration (FTA): safety-sensitive transit employees
• Pipeline and Hazardous Materials Safety Administration (PHMSA): covered pipeline employees
• U.S. Coast Guard (USCG): covered maritime employees. The Coast Guard is part of the Department of Homeland Security, but its testing uses Part 40 procedures.

Coverage depends on the job duties and the agency rule, not on job title alone. DOT’s Office of Drug and Alcohol Policy and Compliance (ODAPC) offers an “Am I Covered?” decision tool. Employees who are not covered must not be tested under DOT authority, and only covered employees belong in a DOT random pool.

What Does a DOT Drug Test Screen For?

Laboratories test DOT urine specimens for five drug classes, using the cutoff levels listed in 49 CFR 40.85:

• Marijuana (THC metabolite)
• Cocaine (benzoylecgonine metabolite)
• Opioids: codeine, morphine, 6-acetylmorphine (a heroin marker), hydrocodone, hydromorphone, oxycodone and oxymorphone
• Amphetamines: amphetamine, methamphetamine, MDMA and MDA
• Phencyclidine (PCP)

The panel is fixed. Employers cannot add drugs to a DOT specimen or remove any from it. Semi-synthetic opioids such as oxycodone have been on the DOT panel since January 1, 2018.

Is Fentanyl Part of the DOT Panel?

Not as of September 2026. HHS added fentanyl and norfentanyl to the federal testing panels in January 2025. DOT then proposed adding them to Part 40 in September 2025. We found no final DOT rule as of this writing, so DOT tests do not yet include fentanyl. Check ODAPC for updates before relying on this.

Can DOT Tests Use Oral Fluid?

Not yet in practice. A 2023 DOT rule authorized oral fluid testing, but employers may use it only after HHS certifies at least two oral fluid laboratories. DOT’s list of certified oral fluid laboratories shows none. A DOT rule effective June 10, 2026 requires a directly observed urine collection in the limited situations where an oral fluid collection would otherwise be required. Hair testing and instant (point-of-collection) drug tests are not used for DOT drug testing.

When Is a DOT Drug Test Required?

Most DOT agencies use six test types. Exact triggers, deadlines and rates differ by agency, so the details below use FMCSA’s rules for CDL drivers as the example.

Random rates for 2026 differ by agency. FMCSA, FTA and PHMSA set 50% for drugs, FAA sets 25%, and FRA sets 25% or 50% depending on the employee group, according to ODAPC’s random testing rates page.

The FMCSA pre-employment exception is narrow. It applies only if the driver took part in a compliant DOT testing program within the previous 30 days, was tested within the past six months or was in a random pool for the previous 12 months, and no known prior employer has a record of a violation in the previous six months. The employer must also contact the prior testing program and keep the required verification.

How the DOT Drug Test Process Works

1. The employer directs the test. The DER or C/TPA notifies the employee. For random tests, FMCSA drivers must go to the collection site immediately after notification.
2. A trained collector collects the specimen. Every DOT collection is documented on the Federal Drug Testing Custody and Control Form (CCF). The urine is split into a primary and a split specimen. Some collections must be directly observed, including all return-to-duty and follow-up tests and cases with signs of tampering (49 CFR 40.67).
3. An HHS-certified laboratory tests the primary specimen. A result at or above the screening cutoff goes to a confirmation test. The laboratory reports results to the MRO, not to the employer.
4. The MRO reviews the result. For a laboratory-confirmed positive, the MRO offers the employee a verification interview to present a legitimate medical explanation, such as a valid prescription. A state medical marijuana recommendation is not accepted (49 CFR 40.151).
5. The employer receives a verified result. If the MRO verifies a positive result, the employee has 72 hours from notification to ask for the split specimen to be tested at a second laboratory (49 CFR 40.171).

What Should an Employer Do With Each DOT Test Result?

The result the MRO reports determines the employer’s next step. The table below summarizes the Part 40 rules for the most common outcomes.

After a violation, the employee cannot return to safety-sensitive work until completing the SAP process and a negative return-to-duty test. Part 40 does not require the employer to return the employee to that work; that remains a personnel decision. GoodHire’s guide to what happens when an employee fails a drug test covers broader employer considerations. FMCSA-regulated employers also have reporting duties in the FMCSA Drug and Alcohol Clearinghouse, a federal database of CDL drivers’ drug and alcohol violations. Clearinghouse queries and reporting are a separate process from administering a test.

How Is a DOT Drug Test Different From a Non-DOT Test?

Many employers run both: DOT tests for covered employees and company-policy tests for everyone else, or for testing beyond what DOT requires.

Part 40 keeps the two programs apart (49 CFR 40.13). The DOT test must be completed first, and a non-DOT test needs a separate urine void. A DOT specimen cannot be tested for extra drugs. A negative non-DOT result cannot be used to override a DOT result. FMCSA also expects any company-authority policy to be clearly described as the employer’s own policy, not a DOT requirement. GoodHire has separate guides to hair follicle testing and saliva testing for non-DOT programs.

Employer Checklist for a DOT Drug Testing Program

Employers may use service agents for most tasks, but under 49 CFR 40.15 the employer remains responsible for compliance. A basic program includes:

• A written policy that meets your DOT agency’s requirements and separates DOT rules from any company-authority rules
• A named DER and a way to reach the DER during testing hours
• Qualified service agents: collection sites with trained collectors, an HHS-certified laboratory, an MRO and access to SAPs
• A random pool that contains only covered employees, run by a scientifically valid selection method
• Required supervisor training for reasonable suspicion decisions
• A check of each applicant’s prior DOT testing history. FMCSA employers do this mainly through a Clearinghouse query; other agencies use the previous-employer request in 49 CFR 40.25
• Records kept for the periods your agency requires

Common Mistakes to Avoid

• Letting a new hire perform safety-sensitive work before a verified negative pre-employment result arrives
• Using an instant test or a non-federal form for a DOT-required test
• Putting non-covered employees in the DOT random pool, or testing a DOT specimen for extra drugs
• Treating a cancelled test as a negative for pre-employment purposes
• Retesting some dilute results and not others under the same test type
• Missing post-accident deadlines without recording why the test was not done
• Applying the FMCSA pre-employment exception without verifying every condition

GoodHire’s drug testing page lists DOT drug tests alongside lab-based 4-, 5-, 8- and 10-panel urine tests, with results verified by MROs. Other program elements, such as random pool management, SAP referrals and Clearinghouse obligations, remain the employer’s responsibility unless a service agent is engaged for them.

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Tiffany Conaway covers Checkr’s verification and drug testing offerings, along with occupational health screening, post-hire monitoring, and the candidate experience. Her work helps employers build compliant, candidate-friendly screening programs.