When to start the renewal
The NMC accepts renewal applications up to 12 months before the credential expires. Most candidates start 4–6 months out to leave room for the physical, drug test, and any sea-service paperwork.
Sea service vs open-book exam
Option A: document at least 360 days of sea service in the last 5 years (the same form, CG-719S, that you used for the original credential). Option B: take the open-book renewal exam, which covers Rules of the Road and is typically taken at home.
Other requirements
CG-719K physical (good for 24 months at issuance), drug test program enrolment (random testing pool), valid TWIC card (5-year validity). CPR and First Aid certs that have not expired.
If your credential has expired
Up to 1 year past expiration, you can still renew with the same package — but you may not exercise the credential's authority during the lapse window. After 1 year, you must reapply as a new applicant — full sea-service evaluation, full exam.