Renewal, Grace Period & Document of Continuity

By Captain Mike · 50 years at sea · former MITAGS faculty
Checked against 46 CFR 10.205, 10.227, and 11.201 · September 2026

Every mariner remembers the day their first Merchant Mariner Credential (MMC) arrived in the mail. Fewer keep track of the expiration date on it. Letting a credential lapse, or misunderstanding what the Coast Guard does with an expired one, can cost you months, money, and exams you thought you'd never sit again.

Whether you're sailing full time, working ashore, or stepping away from the industry, here's how the renewal clock works, what happens if you miss it, and how to “park” your license safely.

How long do credentials last?

Credential	Validity
MMC	5 years from the date of issue. National officer and rating endorsements on it share that expiration date. 46 CFR 10.205
STCW endorsements	Printed on the MMC, but several, including Basic Training and Advanced Firefighting, must be revalidated every 5 years through sea service or refresher training.
Medical certificate	Up to 5 years for national service. 2 years for STCW service (1 year if under 18). 46 CFR 10.301
TWIC	Issued by TSA on its own 5-year cycle, separate from the MMC.

Renew early, without losing time

You don't have to wait for the last minute. For a straight renewal, the Coast Guard can post-date your new MMC up to 8 months from the date it accepts your complete application. If your current credential expires within that window, the new one starts on your old expiration date, so you lose nothing. 46 CFR 10.205

To renew, you'll need to meet one professional requirement

Besides the medical certificate, drug test, and application, a renewing deck or engine officer or qualified rating must meet one of these 46 CFR 10.227(e):

At least 1 year of sea service in the past 5 years
Pass a comprehensive open-book exercise
Complete an approved refresher course
At least 3 years in the past 5 working in a position closely related to operating, building, or repairing vessels, or as a Qualified Instructor

What happens if you miss your expiration date?

You can't sailThe moment your credential expires, you may no longer serve under it. Working on an expired credential puts you and the vessel out of compliance with manning requirements.

12-month grace periodYou can still renew up to 12 months after expiration, using the normal renewal requirements above. 46 CFR 10.227(h)

After 12 monthsOfficer and qualified-rating endorsements can still be re-issued, but you must prove your knowledge by completing an approved course or passing the complete original exam. 46 CFR 10.227(i)

It's not “start from scratch.” A lot of mariners believe an expired license is gone for good after a year. It isn't. The regulation calls it re-issuance: instead of the normal renewal options, you complete an approved course for this purpose or pass the full exam for the endorsement. Plan for it, but don't panic.

“Recency” is a different thing

Mariners often say they'll “put the license on recency.” In Coast Guard language, recency actually refers to how fresh your sea time is when you apply for an original officer endorsement or a raise of grade. You need at least 3 months of qualifying service within the past 3 years, or within the past 7 years for service on uniformed-services vessels. 46 CFR 11.201(c)

Even with thousands of lifetime sea days, an upgrade application without recent service will stall until you get back on the water. What mariners usually mean by “parking” a license is the Document of Continuity.

The Document of Continuity: parking your license

If you're moving ashore, retiring for now, or stepping away for family, and you can't or don't want to meet the renewal requirements, you can apply for a Document of Continuity instead. 46 CFR 10.227(g)

Never expiresIt exists only to preserve your eligibility to renew later.

No medical or drug testYou don't need to meet the medical standards, drug testing, professional requirements, or TWIC to get one.

No authority to sailYou cannot serve as a merchant mariner on it.

Two limits people miss

Timing: apply while your MMC is still valid or within the 12-month grace period. Once a credential is more than 12 months expired, it can't be moved into continuity.
National endorsements only: STCW endorsements cannot be placed on a Document of Continuity.

How can I tell if my license is in continuity?

Check your paperwork

If you applied for continuity, the Coast Guard issued you a Document of Continuity. It isn't a sailing credential, and it shows no expiration date.

Use the NMC's online verification tool

The NMC's Mariner Credential Verification tool emails you credential and medical certificate results. You'll need your last name and your mariner reference number. NMC website →

Call the NMC

If you can't find your reference number or aren't sure what you hold, contact the NMC Customer Service Center at 1-888-IASKNMC (1-888-427-5662). They can look up your record.

Caution: if you simply stopped sailing and never applied for a Document of Continuity, your license is not in continuity. It is expired, and the grace-period and re-issuance rules above apply.

What if it's been years?

Scenario A: your endorsements are on a Document of Continuity

Yes, you can get them back, however long it has been. You convert the Document of Continuity back into an MMC by meeting the normal renewal requirements:

Application (CG-719B), marked as a renewalMedical certificate (CG-719K)Drug test (CG-719P)One professional requirement: sea service, open-book exercise, refresher course, or related employment

Most mariners coming back from years ashore won't have the recent sea time, so the open-book exercise or an approved refresher course is the usual route. You do not resit the original exams.

STCW is separate. Because STCW endorsements can't go into continuity, expect to meet the current STCW revalidation requirements, usually refresher training such as Basic Training and Advanced Firefighting, before those endorsements come back. Basic Training refresher vs. revalidation → Check the NMC checklist for each one.

Renewing after September 30, 2029 with STCW Basic Training? You'll also need an approved violence and harassment prevention course, repeated every five years. See the Basic Training update.

Scenario B: your license expired more than 12 months ago and was never put in continuity

Officer endorsements and qualified ratings (AB, QMED, etc.): these can be re-issued, but you must complete an approved course for this purpose or pass the complete examination for original issue. 46 CFR 10.227(i)
Entry-level ratings (such as Ordinary Seafarer, Wiper, or Steward) carry no professional exam, so they're generally re-issued on a new application.
Upgrading afterward is a separate matter: a raise of grade still needs recent sea service under the recency rule above.

Proactive steps

Submit early

Apply up to 8 months ahead. If your credential expires inside that window, the new one starts on your old expiration date.

Watch the 12-month line

If you miss your expiration date, get the renewal in before the 12-month grace period ends. That keeps you on the normal renewal requirements.

Never walk away empty-handed

Leaving the water, even for good? Apply for a Document of Continuity while your credential is still valid or within the grace period. It costs no exams and keeps the door open.

Captain's Tip

Put your MMC, medical certificate, STCW revalidation, and TWIC dates on one calendar, with a reminder 9 months before each. Four different clocks are running, and it only takes one to stop you at the gangway.

Ready to apply? Applications now go through Navita, the Coast Guard's online credentialing system. It changes how you apply, not what you need. Navita: what changed →

Official sources

Where this fits in your journey

Will I pass the medical?What is STCW, and how is it revalidated?Document my sea service All credentialing resources