How to verify a DEA number

The DEA number format, what each prefix letter means, and the check-digit arithmetic worked step by step — plus how a DEA number differs from an NPI.

DEA Registration

Every entity that handles controlled substances must register with the Drug Enforcement Administration (DEA):

• Pharmacies
• Prescribers (physicians, dentists, veterinarians, etc.)
• Wholesale distributors
• Drug manufacturers
• Others in the controlled-substance distribution chain

Once registered, a DEA number is assigned. The DEA is a division of the US Department of Justice, and federal controlled-substance rules live primarily in 21 CFR.

DEA Number Format

A DEA number contains 9 characters total: 2 letters followed by 7 digits.

• First letter: DEA-assigned registrant-type prefix.
• Second letter: usually tied to the registrant's last name or business name (for individual practitioners, it is the first letter of the prescriber's last name).
• Last seven characters: numerical digits used in the check-digit process.

DEA First-Letter Prefix (Registrant Type)

How to read a physician's DEA number: The first letter is A, B, F, or G (the DEA's historical issuing sequence for individual practitioners). The second letter is the first letter of the prescriber's last name. Seven digits follow. Example format: AS1234563 for Dr. Smith.

Exam Tip: A DEA number beginning with M indicates a mid-level practitioner (NP, PA). An A, B, F, or G prefix indicates a physician or other individual practitioner.

DEA Number Check-Digit Algorithm

The verification method for a DEA number:

1. Add the 1st, 3rd, and 5th digits together.
2. Add the 2nd, 4th, and 6th digits together, then multiply that sum by 2.
3. Add the two results from steps 1 and 2.
4. The last digit of that sum should equal the 7th digit of the DEA number.

Worked Example — Dr. Thomas Jones: AJ5641233

1. Verify the letters: "A" = practitioner type; "J" = first initial of Dr. Jones' last name.
2. Add the 1st, 3rd, and 5th digits: 5 + 4 + 2 = 11.
3. Add the 2nd, 4th, and 6th digits: 6 + 1 + 3 = 10. Multiply by 2: 10 × 2 = 20.
4. Add: 11 + 20 = 31. The last digit of 31 is "1," but the 7th digit of the DEA number is "3."
5. Because "1" does not equal "3," this is NOT a valid DEA number.

NPI Number (National Provider Identifier)

Separate from the DEA number, every US healthcare provider is assigned a National Provider Identifier (NPI) — a unique 10-digit number issued by CMS through the NPPES (National Plan and Provider Enumeration System). The NPI identifies the prescriber on prescriptions and insurance claims, but it conveys no controlled-substance authority; a prescriber still needs a valid DEA registration to prescribe scheduled drugs.

Unlike the DEA number's 2-letter/7-digit layout, an NPI is 10 digits with no letters, and its 10th digit is a check digit validated with the Luhn algorithm (the "double-add-double" mod-10 method used on credit cards). The check runs on the first 9 digits after prepending the constant prefix 80840:

1. Prepend 80840 to the first 9 digits of the NPI.
2. Starting from the rightmost digit, double every second digit; if a product is 10 or greater, add its digits together.
3. Sum all of the digits.
4. The check digit is the number that raises that sum to the next multiple of 10, and it must equal the NPI's 10th digit. (For NPI 1234567893, the digits over 80840123456789 sum to 67, so the check digit is 70 − 67 = 3 — a match, so the NPI is valid.)

Exam Tip: Two prescriber identifiers, two different checks. The DEA number uses the add-the-odd-positions / double-the-even-positions method above; the NPI uses the Luhn algorithm with an 80840 prefix. Do not apply the DEA method to an NPI.

Common Traps

Here's where people miss it on Section 2.2:

• Reading "M" as the physician prefix. A DEA number that starts with M is a mid-level practitioner — NP, PA, optometrist, pharmacist with prescriptive authority. Physicians and other individual practitioners start with A, B, F, or G. "M for MD" feels intuitive and is wrong. The first letter is registrant type, not the prescriber's initial.
• Filling a CII written for "5 refills." Zero refills are permitted on Schedule II. Federal law overrides any prescriber marking. A "x 5" notation on a CII script is invalid; each subsequent fill needs a brand-new prescription. Do not extend the CIII/CIV refill rule across the schedule line.
• Transferring a paper CII because the patient asked. CII is generally non-transferable. The narrow exception is an electronic CII prescription, transferred one time, for initial filling, at patient request, when state law permits. Paper CII does not qualify, and the exception ends after the first fill — every subsequent fill requires a new prescription.
• Treating the 72-hour CII verbal emergency as a stand-alone permission. During a qualifying emergency the prescriber may phone in a CII — but only up to the supply needed for the emergency period (about 72 hours), and the pharmacist must receive the original signed written prescription (or compliant electronic) within 7 days. No 7-day paper, no completed transaction.
• Asking for a triplicate DEA Form 222. The legacy triplicate pads were retired in October 2021. The current paper form is the single-sheet DEA Form 222, or the electronic equivalent through CSOS. The exam still tests the form name and current format.
• Paraphrasing the federal transfer warning. The exact label text is: "Caution: Federal law prohibits the transfer of this drug to any person other than the patient for whom it was prescribed." It must appear on every dispensed Schedule II, III, or IV container (21 CFR 290.5 — Schedule V is outside the federal mandate). The PTCE tests the wording verbatim.
• Placing testosterone or buprenorphine/naloxone at CII. Testosterone is CIII. Buprenorphine/naloxone (Suboxone®) is CIII. Students reach for CII because both are tightly controlled in practice, but the federal schedule does not change to match clinical sensitivity.
• Calling pregabalin CIV or tramadol CV. Pregabalin (Lyrica®) is CV. Tramadol (Ultram®) is CIV. Two of the most-tested misplacements on the section. Anchor each by drug, not by class feel.
• Confusing biennial with biannual on the inventory rule. Federal controlled-substance inventory is biennial — every 2 years. Biannual means twice per year. The two words sound identical, and the exam writes the swap as a classic distractor.
• Letting state law slide when it is stricter than federal. When federal and state controlled-substance rules conflict, the stricter rule governs. A federal "permitted" line does not override a state prohibition. Read both before answering.

Quick Review Checklist

A fast scan of the highest-yield Section 2.2 facts. If any line does not land, go back to the matching body section before moving on.

• Governing law — Controlled Substances Act (CSA), enacted 1970; enforced by the DEA (Department of Justice); rules live in 21 CFR.
• Five schedules — CI (no accepted medical use, not dispensed) through CV (lowest abuse potential).
• Schedule anchors — morphine/oxycodone/hydrocodone/fentanyl/methadone and stimulants like methylphenidate and amphetamine salts = CII; testosterone and buprenorphine/naloxone (Suboxone®) = CIII; alprazolam/lorazepam/diazepam, tramadol (Ultram®), zolpidem, phenobarbital = CIV; pregabalin (Lyrica®) and diphenoxylate/atropine (Lomotil®) = CV.
• DEA number format — 2 letters + 7 digits. First letter = registrant type (A/B/F/G physician, M mid-level, P/R manufacturer/distributor, X legacy DATA-waived). Second letter = first letter of the prescriber's last name.
• Check-digit math — add digits 1+3+5; add digits 2+4+6 and multiply by 2; sum the two; the last digit of that sum equals the 7th digit.
• Refill rules — CII: zero refills; CIII/CIV: up to 5 refills within 6 months; CV: no federal refill limit.
• Emergency verbal CII — up to the supply needed for the emergency period (about 72 hours); the prescriber must provide the written/electronic follow-up within 7 days.
• Faxed CII — permitted for LTC, hospice, and home-infusion/IV pain therapy patients.
• CII transfer — generally not transferable; narrow exception is an electronic CII, one time, for initial filling, at patient request, when state law permits.
• Seven required Rx elements — issue date; patient name and address; prescriber name, address, and DEA number; drug name, strength, dosage form, quantity; directions; refill authorization (if any); prescriber signature. Patient SSN is not required.
• Federal transfer warning (verbatim) — "Caution: Federal law prohibits the transfer of this drug to any person other than the patient for whom it was prescribed." Required on every dispensed Schedule II, III, or IV container (21 CFR 290.5; not Schedule V).
• DEA Form 222 — legacy triplicate retired October 2021; the current single-sheet Form 222 allows up to 20 line items (legacy triplicate allowed 10). CSOS is the electronic equivalent and has no line-item limit. (Form 222 ordering workflow is covered in SG 2.3.)
• CMEA — Combat Methamphetamine Epidemic Act, 2005; pseudoephedrine limits 3.6 g/day and 9 g/30 days.
• Records — federal minimum retention 2 years, readily retrievable; CII records filed separately from CIII/IV/V; biennial (every 2 years) inventory.
• Corresponding responsibility — the pharmacist must dispense only for a legitimate medical purpose; filling a suspect CS prescription carries penalties even when the prescriber is the one misprescribing.
• State vs. federal — when the two conflict, the stricter rule governs.

Related

DEA schedules, refills and transfers · What is on the PTCE and how it is weighted · All Federal Requirements guides