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Navy Reserve IMS and MAS Codes: The Full List Explained (2026)

Every Navy Reserve IMS and MAS code in plain English. See what each medical, administrative and training MAS code means, how the IMS codes track a mobilization, and how to clear a code from your record.

By NavyMentor Editorial Team

Published 18 min read

A Navy sailor in a hard hat guides a cargo lift with a rope during mobilization training in Virginia
U.S. Navy photo by Mass Communication Specialist 2nd Class Chandler Ludke

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In this guide

IMS and MAS codes are short codes in a Navy reservist’s record that show whether that sailor can be mobilized. MAS codes track readiness before a mobilization. IMS codes take over once a sailor is picked for one, and follow them through activation, the return home and the rest period afterwards.

This guide lists every current code in both systems, with a plain-English meaning for each. All of it comes from the Navy Reserve’s own guidance, and we link to that document so you can check any code yourself.

If you have just spotted a three-letter code next to your name and want to know what it means, use the tables below. If you want to understand how the whole system works, read on from the top. ⚓

2code systems: MAS before mobilization, IMS during and after
43current MAS codes in three groups
60+IMS codes covering every stage
9steps in the ideal IMS code path

MAS and IMS: what is the difference?

The two systems are easy to mix up, and the Navy’s own guidance warns people not to. Here is the simple version.

  MAS codes IMS codes
Stands for Manpower Availability Status Individual Mobilization Status
When they apply Day to day, before any mobilization From selection for mobilization until dwell time ends
What they answer Is this sailor ready and available? Where is this sailor in the mobilization process?
Groups Medical, administrative, training Processing, activation, deactivation, delays, exemptions, cancellations, availability
Kept in NSIPS NSIPS
Who updates them Mostly your Navy Reserve Center Your Navy Reserve Center, the pay office or Reserve Force headquarters, depending on the code

Think of MAS as your readiness report card. IMS is the tracking number once your package has shipped.

A few terms you will see

  • SELRES: Selected Reserve. Drilling reservists in a pay status.
  • NRA: Navy Reserve Activity. The guidance uses this term for the local command that manages you, such as your Navy Reserve Center.
  • NSIPS: the Navy’s personnel records system, where the codes are stored.
  • CNRF (N35): the office at Navy Reserve Force headquarters that manages mobilization.
  • MRR: Medical Retention Review. A formal review of a medical condition.
  • RLD: Ready Load Date. The date a sailor needs to be ready to go.
  • NMPS: Navy Mobilization Processing Site. Where sailors process on to and off active duty.
  • Dwell time: the protected rest period at home after a mobilization.

How MAS codes work

MAS codes fall into three groups: medical and dental, administrative and training. A sailor can have a code in each group at the same time.

Three ideas explain most of the system:

  • Precedence. Inside each group, codes are ranked. If more than one could apply, the command uses the one with the highest precedence.
  • Periodicity. Most codes have a time limit, shown in days. When that time is up, the command must check whether the reason still exists. It should not simply remove the code and add it again.
  • Not every code stops a mobilization. The guidance flags some codes as ones that do not prevent a sailor from being mobilized. We highlight those rows in the tables.

Four MAS codes are reserved for Reserve Force headquarters: AKE, SAD, TSP and DCO. Local commands do not add or remove these.

Medical and dental MAS codes

These codes track medical and dental issues that could stop a reservist from carrying out active duty orders. They are listed from highest to lowest precedence.

Code What it means Precedence Review period Effect on mobilization
MPQ Not physically qualified, retention not recommended, after a medical review 1 180 days Affects availability
MS2 Medical Retention Review started for a new or worsened condition 2 180 days Affects availability
MSR Medical Retention Review due for its periodic resubmission 3 180 days Affects availability
MS1 Line of Duty (LOD) case started 4 365 days Affects availability
MS3 Temporarily not physically qualified (TNPQ) 5 180 days Affects availability
MPC Pregnant 6 294 days Affects availability
MPP Non-deployable mother with a child under 12 months, or postpartum recovery 7 365 days, removed automatically Deferred until it expires
MP1 Physically qualified but mobilization limited, after a medical review; a waiver may be needed 8 365 days Affects availability
MDT Dental Readiness Class 3: urgent dental treatment needed 9 180 days Does not prevent it
MNN Not physically qualified, retention recommended; deployable, but may need a waiver 10 365 days Does not prevent it
MDF Dental Readiness Class 4: overdue for the annual dental exam 11 180 days Does not prevent it
The easiest code to clear

MDF simply means your yearly dental exam is overdue. Book the exam, get it recorded, and the reason for the code is gone. It is one of the few codes that is completely in your own hands.

Administrative MAS codes

These codes cover paperwork, legal and personal circumstances that could stop a reservist from carrying out orders.

Code What it means Precedence Review period Effect on mobilization
BCG BUPERS Control Group: the record is frozen by Navy Personnel Command 1 None listed Affects availability
AKE Key Federal Employee (headquarters use only) 2 None listed Affects availability
AUP Unsatisfactory participant 3 180 days Affects availability
ACR Approved conditional release from the Navy Reserve 4 180 days Affects availability
AAP Administrative action pending that would prevent mobilization or end drilling status 5 180 days Affects availability
ASF Not eligible for force protection duties 6 None listed Affects availability
APB Enlisted probationary drill status after unsatisfactory participation 7 180 days Affects availability
ARR Retirement request submitted and pending, or approved 8 365 days Affects availability
ACB Not selected for continuation 9 365 days Affects availability
AS2 Within six months of High Year Tenure or statutory attrition 10 180 days Affects availability
TS1 24-month deferment for Navy veterans who join the Selected Reserve in a paid, drilling status 11 730 days, removed automatically Deferred until it expires
AS1 12-month deferment after a mobilization was cancelled close to the ready date 12 365 days, removed automatically Deferred until it expires
ASO Sole surviving son or daughter; limits where the sailor can be sent 13 None listed Does not prevent it
AFP Security clearance records show a problem, such as a revoked or denied eligibility 14 365 days Does not prevent it
ASP Single parent or guardian who needs a family care plan 15 None listed Does not prevent it
ASD Married to another service member and needs a family care plan 16 None listed Does not prevent it
AS3 Non-custodial single parent who does not need a family care plan 17 None listed Does not prevent it
MPT Failed the most recent Physical Fitness Assessment 18 180 days Does not prevent it
OAT Government travel charge card is revoked or suspended 19 365 days Does not prevent it

Two of these are deferments rather than problems. TS1 protects a Navy veteran who has just joined the Selected Reserve from being involuntarily mobilized for 24 months. AS1 gives 12 months to a sailor whose mobilization was cancelled at the last minute. In both cases the sailor can choose to waive the deferment and volunteer.

Training MAS codes

These codes cover reservists who are in a special training programme, or who have not yet finished training they need.

Code What it means Precedence Review period Effect on mobilization
SAD Approaching sanctuary: 16 or more years of active duty (headquarters use only) 1 None listed Affects availability
DAP Administrative separation pending, package submitted 2 180 days Affects availability
TMS Attending an authorised medical or dental school 3 1,460 days Affects availability
DCO Direct commission officer who still needs the indoctrination course (headquarters use only) 4 365 days Affects availability
TBH Has not finished community-specific training or credentials needed to mobilize (headquarters use only) 5 730 days Affects availability
TSP Officer released early from active duty to play in a U.S. professional sports league (headquarters use only) 6 365 days Affects availability
TS2 Religious Program Specialist assigned to a Marine Corps unit without the required combat skills qualification 7 365 days Affects availability
PRO 36-month deferment for health care professional officers who join as drilling reservists 8 1,095 days Deferred until it expires
TIW Information Warfare officer who has not finished the required training or qualification 9 1,095 days Affects availability
TRP In rating or designator conversion training (PRISE-R) 10 545 days Affects availability
VS1 On definite (temporary) recall 11 None listed Does not prevent it
OWS On Active Duty for Operational Support (ADOS) orders 12 None listed Does not prevent it
TBX Has not finished prescribed training courses for individual readiness 13 None listed Does not prevent it

Old MAS codes you may still see mentioned

Some codes are no longer used or are kept as spares. They still turn up in old paperwork and forum posts.

Old code What it used to mean
VOL Volunteer, fully available and ready for mobilization
VLI Volunteer for duty inside the continental United States only
VLO Volunteer for duty overseas only
VLU Volunteer to go with the assigned unit only
OTN On active duty for training for less than 180 days, not in support of operations
OTS On active duty for training for less than 180 days, in support of a crisis
TDX Completed initial active duty for training
TS3 Officer assigned to the Chaplain Candidate Program
TRL Attending valid religious training
TCB, THS Spare or headquarters-only codes

How IMS codes work

IMS codes start the moment Reserve Force headquarters picks a sailor for a mobilization. From then on, the IMS code tells everyone exactly where that sailor is in the process.

Two rules are worth knowing before you read the lists:

  • IMS replaces MAS for a while. Once a sailor has the code R##, readiness is tracked using IMS codes only. MAS codes come back into play after the mobilization is finished or cancelled.
  • The record locks. While a sailor has an activation code, the record is locked. MAS codes cannot be changed and the sailor cannot be separated without headquarters stepping in.

The ideal path

The guidance describes one “ideal” run of codes. It is the easiest way to understand the whole system.

  1. R## — identified. Headquarters has picked you for a mobilization.
  2. RC1 — notified. Your Navy Reserve Center has told you.
  3. RC2 — screened. You have finished the medical and dental screening.
  4. RC2.5 — ready. All admin, medical, dental and training requirements are done. You are waiting for your start date.
  5. RC3 — reported. You have reported for activation as ordered.
  6. RM1 — on active duty. The system shows you gained to active duty.
  7. RD1 — released. You have been released from active duty and sent back to your Navy Reserve Center.
  8. RD2 — back drilling. You have reported back and are in a drilling status.
  9. RDA — dwell complete. Your rest period is over and you can be picked again.
RC3 is a one-way door

The guidance notes that RC3 closes out your reserve pay record. After that, drills can no longer be entered, and the mobilization orders cannot simply be cancelled. If something stops you going at that point, headquarters has to issue demobilization orders instead.

IMS codes: activation processing

Code What it means Who sets it
Blank Not identified for recall or mobilization; no action needed Not applicable
RYY Tagging process started (headquarters use only) Headquarters
RXX Tagging process cancelled (headquarters use only) Headquarters
R## Identified for recall or mobilization Headquarters
RC1 Reservist has been told in person or by phone that they are identified Navy Reserve Center
RC2 Expeditionary medical and dental screening completed Navy Reserve Center
RC2.5 All requirements complete; waiting for the activation start date Navy Reserve Center
RC3 Reported for activation as directed Navy Reserve Center
ROC Orders cancelled before they were carried out Headquarters
RU1 Unable to contact the reservist; still trying Navy Reserve Center
RU2 30 days or more have passed and the reservist cannot be found; no longer trying Navy Reserve Center
RUA Notified but did not report as ordered: unauthorised absence Navy Reserve Center
RDD Declared a deserter Navy Reserve Center

ROC is a general “dropped” code. The guidance says it should only be used when no more specific code fits. It does not stop a sailor from being picked for a later mobilization.

IMS codes: on active duty

Code What it means
RM1 Gained to active duty (set by the system)
RVC Serving on voluntary orders
RM2 Reported to the final duty station
RM3 Remaining on active duty
RM4 Reassigned to another command
RM5 Administrative hold
RM6 Judicial hold
RM7 Medical hold, delay or evaluation
RM8 Discharged from active duty
RM9 On the Temporary Disability Retired List
RMD Retired from active duty
RML Released to the processing site for deactivation
RMP Reported to the processing site for deactivation

These codes reflect active duty transactions, so they should update on their own. A switch from RM1 to RVC shows that a sailor moved from involuntary orders to voluntary ones.

IMS codes: coming home and dwell time

Code What it means
RD1 Released from active duty and ordered back to the Navy Reserve Center (set by the system)
RD2 Reported back and in a drilling status
RDA Dwell time has expired; available for an involuntary activation again (set by the system)

The guidance says the RDA code is generated using a one-to-five ratio of time mobilized to time at home, based on Navy policy. A sailor in dwell can still volunteer by signing a waiver.

IMS codes: delays and exemptions

Code What it means
D7G Delay of 1 to 3 days granted by the Navy Reserve Center commanding officer
D3P Delay of 4 to 30 days applied for and pending
D3G Delay of 4 to 30 days granted by headquarters
D6P Delay of 31 to 60 days applied for and pending
D6G Delay of 31 to 60 days approved by a special cases board
HPP Personal hardship exemption pending
HPG Personal hardship exemption granted
HCP Community hardship exemption pending
HCG Community hardship exemption granted

The pattern is easy to read once you see it. A code ending in P means pending. A code ending in G means granted.

IMS codes: cancellations

Cancellation codes explain why a sailor was dropped from a mobilization. They fall into four groups.

Group Code What it means
Medical DMC Non-deployable mother with a child under 12 months
DMT Temporary medical deferment, awaiting a decision
EMP Pregnant
EMN Not physically qualified for mobilization
EMD Deceased
Training DTH High school student under 20 years old
DTX Has not completed basic or equivalent training
DTR Attending validated religious leader training
DTC In designator or rating conversion training
DTM Attending an authorised medical or dental school
Judicial JDP Judicial proceedings pending (entered by the local chain of command)
DJP Judicial proceedings pending (entered by headquarters)
EJC Confined by civil authorities
EJM Confined by military authorities
EJP On probation and may not leave the court’s jurisdiction
Administrative EAK Key employee
EAE Being separated: erroneous, defective or fraudulent enlistment
EAD Being separated: drug or alcohol abuse
EAP Being separated: unsatisfactory participation
EAC Being separated: conscientious objector
EAS Being separated: sole surviving son or daughter
EAM Being separated: misconduct
EAR Processing for retirement
EAO Not extending obligated service
EAT Enlisted in the active component
Your civilian job is not a way out

The guidance is clear that once a mobilization is ordered, no deferment, delay or exemption is granted because of civilian employment. The “key employee” code is for a small group whose jobs were formally designated in advance.

IMS codes: available again

Code What it means
NAO The delay, exemption or cancellation has ended or been resolved; fully available for activation
NAI Available for activation inside the continental United States only

When the reason for a delay or cancellation goes away, the code should be updated to NAO straight away. That tells headquarters the sailor is ready again.

How to find out which code you have

You do not have to guess. The system is built so that someone reviews your codes every month.

  1. Ask your unit leadership. Unit commanding officers get a MAS code listing each month and are required to review it.
  2. Ask your Navy Reserve Center. Each one has a MAS Code Coordinator whose job is to assign and update the codes.
  3. Ask what the code needs. Find out exactly what would clear it: an exam, a form, a course or a decision from someone else.
  4. Follow up. Once you have fixed the cause, check that the code was actually removed. A code that lingers can hold up orders.

Real-life situations

1. A code appeared and nobody told you why

Start with the tables above, then ask your unit. Most codes have an ordinary explanation, such as an overdue dental exam or a missing training course.

2. You want to volunteer for orders

A code that stops mobilization will get in the way. Ask what it would take to clear it before you apply. If you hold a deferment code, you can usually waive it in writing.

3. You just left active duty and joined the Reserve

You may have the TS1 code. It is a 24-month deferment from involuntary mobilization for Navy veterans who join in a paid, drilling status. It is there to protect you, not to flag a problem.

4. You have been told you are “tagged”

That means your IMS code is now R##. Expect a call from your Navy Reserve Center, then screening and paperwork. Use the ideal path above to see what comes next.

5. A family emergency comes up before you leave

Tell your chain of command at once. There are codes for short delays and for hardship exemptions, but they have to be applied for and approved.

Common mistakes (and the fix for each)

⚠️ Mistake: Treating MAS and IMS as the same thing.

✅ Fix: MAS is readiness before mobilization. IMS tracks the mobilization itself.

⚠️ Mistake: Assuming every code means you cannot go.

✅ Fix: Several codes do not prevent a mobilization. Check the last column of the tables.

⚠️ Mistake: Ignoring a code because it seems minor.

✅ Fix: Even a small code can slow down orders. Clear it while it is easy.

⚠️ Mistake: Expecting a code to drop off by itself.

✅ Fix: Only a few codes are removed automatically. The rest need someone to update the record.

⚠️ Mistake: Trusting an old code list from a forum.

✅ Fix: Codes are retired and added. Use the current official guidance.

⚠️ Mistake: Waiting until you are tagged to sort out problems.

✅ Fix: Fix medical, dental and admin issues during normal drill weekends.

Pro tips for staying ready

  • Keep your dental and medical exams current. They cause the most common codes.
  • Keep your family care plan up to date if you are a single parent or part of a dual-military couple.
  • Protect your travel card. A suspended card creates its own code.
  • Pass your fitness assessment. A failure is recorded as a code too. Our guide to the Navy fitness test can help.
  • Keep copies of your paperwork. Orders, medical letters and waivers are easier to sort out when you have them to hand.
  • Ask at every drill weekend if anything has changed on your record.

Useful gear for getting mobilization-ready

A mobilization means a lot of paper and a lot of packing. These three items help with both. We chose them by researching what each one does and who it suits. We have not tested them hands-on, and we list the trade-offs. Read how we choose products.

Three practical items for mobilization prep
ProductBest forKey featurePrice levelLink
Best for paperworkSooez 13-Pocket Expanding File FolderKeeping orders and records in one place13 labelled pockets, letter size BudgetSee on Amazon (opens in a new tab)
Best for documents at homeSentrySafe Fire-Resistant ChestProtecting papers your family may needFire tested, with a key lock Mid-rangeSee on Amazon (opens in a new tab)
Best for packingRothco Heavyweight Canvas Duffle BagHauling gear to and from ordersTop-loading heavyweight canvas BudgetSee on Amazon (opens in a new tab)

Price level is a broad guide, not a live price. Scroll the table sideways on small screens.

Best for paperwork

Sooez 13-Pocket Expanding File Folder

Budget

An accordion-style folder with 13 tabbed pockets. Mobilization paperwork piles up fast: orders, medical forms, powers of attorney, pay documents. A folder like this keeps it in one place that you can grab on the way out of the door.

Ideal for: Reservists who want every form to hand at each stage of processing.

  • Expanding spine for more capacity
  • Tabbed pockets for sorting
  • Light and easy to carry
Brand
Sooez
Pockets
13, with tabs
Paper size
Letter and A4
Material
Polypropylene
Size
about 13 x 9.5 inches

What we like

  • Inexpensive
  • Keeps documents in order
  • Fits in a backpack

Trade-offs

  • Not waterproof or fire resistant
  • Plastic clasp can wear with heavy use
  • No lock, so not for sensitive originals
Best for documents at home

SentrySafe Fire-Resistant Chest (0.25 cubic feet)

Mid-range

A small fire-resistant chest for the papers your family may need while you are away, such as wills, powers of attorney, birth certificates and insurance policies. The listing says it is UL classified for half an hour of fire endurance at 1,550°F.

Ideal for: Keeping original documents safe and easy for a spouse or relative to find.

  • Fire-resistant construction
  • Privacy key lock
  • Carrying grips
Brand
SentrySafe
Capacity
0.25 cubic feet
Lock
Key
Fire rating in the listing
UL classified, 30 minutes at 1,550°F
Size
about 15.3 x 12.1 x 6.3 inches

What we like

  • From an established safe maker
  • Stated, tested fire rating
  • Small enough for a closet shelf

Trade-offs

  • A privacy lock, not theft protection
  • Holds papers flat, so space is limited
  • Not rated for flooding in this listing
Best for packing

Rothco Heavyweight Top-Load Canvas Duffle Bag

Budget

A plain, tough, top-loading canvas duffle in the classic military style. It swallows bulky gear and stands up to being thrown around. Check your orders and any packing list first, because you may be issued bags or have size limits to meet.

Ideal for: Reservists who need a spare heavy-duty bag for travel and training.

  • Dense, abrasion-resistant canvas
  • Wide top opening
  • Heavy-duty stitching
Brand
Rothco
Material
Heavyweight cotton canvas
Opening
Top load
Handles
Reinforced

What we like

  • Simple and durable
  • Large capacity
  • Low price

Trade-offs

  • No wheels
  • No internal pockets or organisation
  • Canvas is not waterproof

Getting ready to go?

Use our packing checklists so nothing gets left behind.

Open the packing checklists

Frequently asked questions

What does MAS code mean in the Navy Reserve?

MAS stands for Manpower Availability Status. MAS codes show medical, administrative or training issues that affect whether a Selected Reservist is ready and available to mobilize.

What does IMS code mean in the Navy Reserve?

IMS stands for Individual Mobilization Status. IMS codes track a reservist from the point they are identified for mobilization, through activation and deactivation, until their dwell time ends.

What does the IMS code R## mean?

It means the reservist has been identified for recall or mobilization by Reserve Force headquarters. It is often called being tagged.

Which MAS codes do not stop a mobilization?

According to the January 2023 guidance, the codes MDT, MNN, MDF, ASO, AFP, ASP, ASD, AS3, MPT, OAT, VS1, OWS and TBX do not preclude mobilization.

How do I get a MAS code removed?

Fix the cause, then ask your Navy Reserve Center to update your record. For example, an overdue dental exam code is cleared by completing the exam. Only a few codes are removed automatically.

Where are IMS and MAS codes recorded?

In NSIPS, the Navy Standard Integrated Personnel System. Your unit leadership and your Navy Reserve Center can tell you what is on your record.

Your quick-reference checklist

  • MAS = readiness before mobilization. IMS = tracking the mobilization.
  • MAS groups: medical, administrative, training.
  • R## means you have been identified, or “tagged”.
  • Ideal path: R##, RC1, RC2, RC2.5, RC3, RM1, RD1, RD2, RDA.
  • RC3 closes your reserve pay record.
  • P means pending, G means granted on delay and hardship codes.
  • NAO means fully available again.
  • Ask your unit each month what is on your record.
  • Clear small codes early, before they hold up orders.

The codes can look like alphabet soup at first. But each one is just a short answer to a simple question: is this sailor ready, and if not, why not? Once you can read them, you can do something about them. ⚓

Sources

Facts last checked against these sources: October 2026.

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