Both licensing exam series limit how often you can sit each exam, and both close the door once you pass. The rules differ in the details, and DO students who take both have to track two sets. This guide covers the USMLE rules first, then COMLEX-USA, then compares them.
Part 1: USMLE attempt limits
1. Know the 12-month rule
You may not take the same Step more than three times within a 12-month period (USMLE, eligibility). This applies to each Step separately: three attempts at Step 1 in 12 months does not affect Step 2 CK.
2. Know the rule for a fourth attempt
A fourth attempt at the same Step must be at least 12 months after your first attempt and at least six months after your most recent attempt. Both conditions have to be met, so the later of the two dates is your earliest possible fourth attempt.
| Example | Attempt dates | Earliest fourth attempt |
|---|---|---|
| Attempts every 4 months | Months 0, 4, 8 | Month 14 (6 months after month 8 is later than 12 months after month 0) |
| Attempts every 2 months | Months 0, 2, 4 | Month 12 (12 months after month 0 is later than 6 months after month 4) |
| Spread out | Months 0, 6, 11 | Month 17 (6 months after month 11) |
3. Know the overall cap
If you have attempted a Step four or more times, including incomplete attempts, and have not passed, USMLE says you are ineligible to apply for any Step in the sequence (USMLE). The cap is per Step, but its consequence covers the whole sequence.
4. Count incomplete attempts
Incomplete attempts count toward the limits, and they may appear on your transcript as incomplete. Starting an exam and leaving early is therefore not a free try; if you are unwell or unprepared, rescheduling before test day is the safer choice where your registration allows it.
5. Understand that a pass closes the door
If you pass a Step, you are not allowed to retake it. The only exception USMLE lists is retaking to comply with a time limit imposed by a U.S. medical licensing authority or another authority the program recognises. USMLE also notes that if you retake a passed Step 1 or Step 2 CK for that reason and fail, you lose eligibility for Step 3.
In practice this means your first passing score is final. On Step 2 CK and Step 3, where the score is a number, there is no way to raise it later.
6. Plan the date around readiness, not the rules
The rules tell you the earliest date you could retake, not the best one. Because each attempt counts and every result stays on your transcript, we pick a retake date from practice exam results under test conditions, with a margin above the passing standard.
For Step 1 that means consistently passing practice results; for Step 2 CK and Step 3, a margin above 218 and 200. See current passing scores.
7. Check the rules again before you register
Rules change. Before you book, read the current eligibility page on usmle.org and check any additional rules from your school, the ECFMG if you are an international graduate, or the state licensing authority you plan to apply to, since some licensing authorities set their own limits on attempts.
Part 2: COMLEX-USA attempt limits
8. Know the four-attempt limit
NBOME limits candidates to a total of four scored attempts for each examination level (NBOME Bulletin 2026-2027). The limit applies per level, so attempts at Level 1 do not use up attempts at Level 2-CE.
9. Know the 12-month rule
You are also not permitted to take a level more than four times within a 12-month period, and that count includes incomplete or voided attempts. In practice the four-scored-attempt limit usually binds first, but the 12-month rule is a reminder that voided and incomplete attempts still count against you.
10. Understand that you cannot retake a pass
NBOME says candidates who have passed an examination may not retake it to improve their score or for any purpose other than to pass a previously failed examination. The same rule appears in the candidate agreement: no level may be taken for practice or to improve a score.
On Level 2-CE and Level 3, which report three-digit scores, your first passing score is the one that stays.
11. Know the rare exception
NBOME describes a narrow exception: a one-time additional attempt at the explicit request of a medical licensing agency, which requires a written petition from that agency and confirmation of good standing from your college of osteopathic medicine. It is not a routine option, and the details are set out in NBOME's petition materials and Bulletin.
12. See how the limit plays out across levels
| Level | Scoring | Attempts allowed | Score release |
|---|---|---|---|
| Level 1 | Pass/fail | Four scored attempts | Generally 2-6 weeks after the window closes |
| Level 2-CE | Three-digit, pass at 400 | Four scored attempts | Generally 2-6 weeks |
| Level 3 | Three-digit, pass at 350 | Four scored attempts | 8-10 weeks |
Scoring and release figures from NBOME, scoring and reporting. The long Level 3 release window matters if you need to plan a retake: a result that takes two months to arrive leaves less time before the next window.
13. Plan each attempt as if it were the last
With four attempts per level, the gap between a first fail and running out of attempts can be smaller than it looks. We treat every retake as a planned attempt: diagnose why the last one fell short, rebuild around that, and choose the date from practice results rather than from the calendar.
“I worked with Alex and Sean during my COMLEX Level 1 retake. At that point, I had already retaken the exam twice without success and was preparing for my last allowed attempt. Working with them completely changed my life.”
— M, Google review, June 2026
14. Check state and school rules too
NBOME recommends checking the FSMB website for the most up-to-date state licensure requirements, because licensing boards can set their own attempt limits. Your college of osteopathic medicine may also have its own rules on how many attempts it allows before graduation.
USMLE and COMLEX rules side by side
| Rule | USMLE | COMLEX-USA |
|---|---|---|
| Attempts in 12 months | No more than 3 at the same Step | No more than 4 at the same level, counting incomplete or voided |
| Total cap | 4 attempts without a pass ends eligibility for every Step | 4 scored attempts per level |
| Waiting rule for a later attempt | 4th attempt at least 12 months after the 1st and 6 months after the latest | Covered by the 12-month count |
| Retake after a pass | Only to meet a licensing time limit | Not allowed, except a one-time request from a licensing agency |
| Incomplete attempts | Count toward limits | Count toward the 12-month limit |
Sources: USMLE eligibility and NBOME Bulletin 2026-2027.
Worked example: a DO student with one fail on each series
Say a DO student fails COMLEX Level 2-CE in June and USMLE Step 2 CK in August. Under the COMLEX rules they have three scored Level 2-CE attempts left; under the USMLE rules they have used one of three Step 2 CK attempts for that 12-month window, and one of four overall. Neither limit forces a rush, but every further attempt narrows both. In our experience the safer path is to choose one exam to retake first, pass it with margin, and only then decide whether the second is needed for the programs being applied to.
Before you book a retake: a checklist
- Count your attempts at that exam, including incomplete or voided ones.
- Work out the earliest date the rules allow, then ignore it until your practice data says you are ready.
- Check your school's policy on retake timing and on rotations or graduation.
- If you are an international graduate, check ECFMG requirements as well.
- Check the attempt limits of the state where you plan to be licensed; FSMB lists state requirements.
- Take at least two practice exams under real timing, spaced out, with results above the passing standard.
- Book the date with time left to move it if the last practice result disappoints.
This checklist is our standard process. The rules set the outer limits; the data decides the date.
Planning a retake with us
We start from your score report and practice data and set the date from readiness, not from the earliest date the rules allow. See failed Step 1, failed Step 2 CK, failed COMLEX, or book a free intro consult.