What Is a Service Number and How to Find One

You've found a name on a medal, a faded photo with a number scrawled on the back, or a family story about someone who served. Now you're trying to find their war records - and every guide you read says you need a service number. But what actually is a service number? What do the letters in front of it mean? And if you don't have one, how do you find it?

A service number is the unique identifier assigned to every person who enlisted in Australia's armed forces. It's the key that unlocks their service record at the National Archives of Australia. Without it, you're searching by name alone - and if your ancestor was named John Smith, that's a long afternoon. With it, you can go straight to the right file.

This guide explains how Australian service numbers work across all three branches and both World Wars, what every prefix means, and exactly where to go if you don't have a number yet.

First World War: Regimental numbers (not service numbers)

If your ancestor served in the AIF during World War I, they didn't receive a "service number" in the modern sense. They received a regimental number - and the system had some significant quirks that catch researchers off guard.

Each battalion, light horse regiment, or corps issued its own sequence of numbers, usually starting from 1. The Regimental Sergeant Major typically received number 1 as a mark of seniority. These numbers weren't unique across the army. A soldier numbered "1234" in the 1st Battalion was a completely different person from soldier "1234" in the 7th Battalion.

Officers and nurses weren't issued regimental numbers at all. If your ancestor was an officer during WWI, their records are identified by name and rank rather than a number.

When soldiers transferred between units, they sometimes kept their existing number (if it wasn't already taken in the new unit), received a new one, or had a letter suffix added to avoid duplication - like 1234A or 567B. Re-enlisted soldiers often had the letter "R" appended.

From 1917, the AIF changed how reinforcements were allocated. Instead of being assigned to specific units before departure, they were drawn from a common pool as "general reinforcements" and given unique numbers in the 50,000 to 80,000 range. This was the first step towards the unique numbering system that would come after the war.

The regimental system was abolished in 1921 and replaced with unique army numbers - one number per person, retained for their entire period of service.

Second World War: The prefix system explained

By World War II, the problems with the old regimental system had been acknowledged. Every member of the Second Australian Imperial Force was allocated a unique service number - called an Army number - that belonged to them alone and was never reissued to anyone else.

These numbers had a prefix made up of one or more letters, followed by a number. The system tells you two things immediately: where the person enlisted, and which force they belonged to.

State prefixes - where they enlisted

The first letter indicates the Military District (essentially the state or territory) where the person signed up:

• N - New South Wales
• V - Victoria
• Q - Queensland
• S - South Australia
• W - Western Australia
• T - Tasmania
• D - Northern Territory

Two additional prefixes were used for Europeans who enlisted overseas: NGX for those who enlisted in New Guinea and PX for those who enlisted in Papua.

The "X" - what it means

The letter X after the state prefix indicates enlistment in the Second Australian Imperial Force. So NX means "New South Wales, 2nd AIF" and VX means "Victoria, 2nd AIF". General Sir Thomas Blamey, who commanded all Australian forces during WWII, was famously VX1 - the first person to enlist in Victoria.

Additional prefix letters

As the war progressed, extra letters were added to handle different enlistment situations:

• F - Female. Added to indicate women's service (e.g. VFX61330 was a woman who enlisted in Victoria for the 2nd AIF)
• P - Permanent Military Forces. Indicates the person was serving in the regular army rather than the volunteer AIF (e.g. VP3596)
• M - Initially used for CMF (Citizen Military Forces / Militia) members who volunteered for the 2nd AIF. This practice was later discontinued

What about Militia and CMF numbers?

Not everyone who served in WWII joined the AIF. The Citizen Military Forces (also called the Militia) used the same state prefixes but without the "X". Soldiers who transferred from the Militia to the AIF often kept their old number with 100,000 added. Permanent Military Forces (PMF) officers had 200,000 added.

This is why you'll sometimes find two different numbers for the same person - one for their Militia service and one for their AIF service. It's not an error; it's how the system worked.

A low number means early enlistment

Because numbers were issued sequentially from 1 within each state, a low number generally means the person enlisted early in the war. NX1 enlisted before NX50000. This can be a useful clue if you're trying to narrow down when your ancestor signed up.

Royal Australian Navy service numbers

The Navy had its own system, separate from the Army. During WWII, RAN officers weren't assigned official service numbers - they received "pay numbers" used for administrative purposes. Permanent Naval Force ratings (non-commissioned sailors) received official numbers without any letter prefixes.

Naval reserve ratings had prefixes indicating their port of enlistment: S for Sydney, PM for Port Melbourne, F for Fremantle, B for Brisbane, H for Hobart, PA for Port Adelaide, and W for Williamstown.

Members of the Royal Australian Naval Volunteer Reserve (RANVR) had an oblique stroke and "V" added to their prefix (e.g. PA/V). It wasn't until 1966 that all naval personnel were issued personal numbers with standardised category prefixes.

RAAF service numbers

The Royal Australian Air Force used a different approach again. During WWII, RAAF service numbers didn't have letter prefixes like the Army. They were plain numbers, issued in blocks allocated by state.

Numbers from 400,001 to 459,999 were reserved for aircrew, while ground crew received numbers from 1 to 299,999. When service numbers were in active use, they were sometimes preceded by a letter indicating the member's status category - but these weren't part of the official number itself.

Each RAAF service number was unique and was never reassigned to another member. If you've got an RAAF number, there's only one person it belongs to.

How to find a service number you don't have

If you're starting with just a name and a family story, here are the best places to find the service number - in order of most likely to give you a quick result.

1. DVA Nominal Rolls

The Department of Veterans' Affairs publishes online Nominal Rolls for WWII, the Korean War, the Vietnam War, and the First Gulf War. Search by surname at nominal-rolls.dva.gov.au. The WWII roll alone covers over one million personnel across Army, Navy, RAAF, and Merchant Navy. It'll return the service number, rank, unit, dates, and place of enlistment.

2. AWM Embarkation Roll (WWI)

For WWI, the Australian War Memorial's Embarkation Roll lists approximately 330,000 AIF personnel as they departed Australia. It includes their regimental number, unit, age, occupation, address, and next of kin. The AWM People search page lets you search this and several other nominal rolls at once.

3. The AIF Project (WWI)

Maintained by UNSW Canberra, the AIF Project is a searchable database of the 330,000 men and women who served overseas in the First AIF. It draws data from multiple sources and can be easier to search than RecordSearch if you're starting from scratch.

4. NAA RecordSearch (all conflicts)

If the nominal rolls don't return a result, try the National Archives of Australia's RecordSearch database using the NameSearch function. Enter the surname, select the relevant conflict category, and browse the results. The item titles usually include the service number, place of birth, and place of enlistment - which helps when there are multiple people with the same name. For a full walkthrough, see How to Request War Records from the National Archives of Australia.

5. Family documents

Don't overlook what's already in the house. Service numbers appear on discharge certificates, letters of service, pay books, identity discs (dog tags), medals (sometimes engraved), and old correspondence from the Department of Defence or Repatriation. Even a number scratched onto the back of a photograph can be enough to start a search.

Once you've got the number - what next?

A service number on its own tells you when and where someone enlisted. But the full service record - the attestation form, the service and casualty form, the discharge papers - that's where the real story lives. It's also where things get hard to read. Military abbreviations, handwritten entries, unit codes, and dates that don't make sense without historical context.

Decode My Digger takes those records and turns them into something a family can actually understand - every abbreviation translated, every date mapped to real events, every posting explained in plain language.

Quick reference: WWII Army service number prefixes

Quick reference: Where to find service numbers

Frequently asked questions

What does NX mean on an Australian service number?

NX means the person enlisted in New South Wales (N) in the Second Australian Imperial Force (X). The first letter indicates the state or territory of enlistment, and the X indicates membership of the 2nd AIF during World War II. Other state prefixes include VX (Victoria), QX (Queensland), SX (South Australia), WX (Western Australia), TX (Tasmania), and DX (Northern Territory).

How do I find my ancestor's Australian service number?

The fastest way is to search the DVA Nominal Rolls at nominal-rolls.dva.gov.au. Enter the surname and select the relevant conflict. For WWI, try the AWM's Embarkation Roll or the AIF Project. Once you've got the number, search RecordSearch at the National Archives to find the full service record.

Did Australian WWI soldiers have service numbers?

Yes, but they were called regimental numbers and they weren't unique across the whole army. Each battalion or corps issued its own sequence starting from 1, so multiple soldiers could share the same number. Officers and nurses weren't issued numbers at all. The system was replaced with unique army numbers in 1921.

What do RAAF service numbers look like?

During WWII, RAAF numbers didn't have letter prefixes. They were plain numbers issued in blocks by state. Numbers 400,001-459,999 were for aircrew; 1-299,999 for ground crew. Each number was unique and never reassigned.

Why does my ancestor have two different service numbers?

It's common. Someone who served in the Militia (CMF) and then volunteered for the 2nd AIF would have both a CMF number and an AIF number. Militia members who transferred often kept their old number with 100,000 added. Post-war service brought further number changes as systems evolved.

When did Australia stop using service numbers?

Service numbers were progressively phased out in 2000 and 2001. The Department of Defence replaced them with employee numbers as part of an integrated personnel management system called PMKeyS.