How to join 21 SAS
By Deepak Shukla · Historical account and source-led commentary
The first step towards joining 21 SAS Reserve is to check the British Army's current SAS Reserve role listing and speak with its recruiting team. The Army accepts expressions of interest from some people without previous military service, but requires initial Army training and relevant experience before SAS selection. My application diary is from 2015–2016 and is not a substitute for today's eligibility advice.
Step 1 — contact the unit
Start with the official UK Special Forces Reserve and Army Jobs pages, which describe the initial application route and broad recruiting regions. Ask the recruiting team which route fits your circumstances before arranging travel or relying on historic addresses. My own first step was an application, not a direct entry into selection.
Step 2 — paperwork, medical, references
The Army will explain the documents, service history, medical and other eligibility information it needs, and which basic training route applies. An application can involve administrative steps before any demanding physical training begins. Do not rely on my old paperwork or a forum checklist as an up-to-date or individual assessment.
Step 3 — briefing and assessment
The Army publicly describes a briefing course as part of its selection route. But for civilians it also sets out necessary Army basic and initial trade training and experience before selection. My published ATC Pirbright diary comes from the initial Army-training part of my journey; it should not be mistaken for an account of passing UKSF Reserve selection.
Step 4 — prepare safely and with the right information
Find out which current assessments apply to you and ask official staff about what they expect. General aerobic conditioning, strength and sensible recovery may be valuable, but a fixed online schedule cannot account for health, experience or injury risk. Qualified coaches can help adapt training, while the Army alone can confirm selection standards.
How long should you give yourself?
There is no dependable single timeline for every applicant. The preparation and initial Army-training requirements depend on your background, current fitness, application dates and the unit's intake. Ask for a realistic sequence and then plan around work, recovery and the wider obligations of service rather than promising to be ready after a fixed number of weeks.
A note on accuracy
Entry criteria, standards and selection dates are set by the Army and change over time. Take anything current from the Army's own UK Special Forces Reserve pages; take everything below as one applicant's experience.
Sources and current requirements
My experience dates from 2014–2016. Eligibility, fitness standards and the selection process change, so for anything current use the Army's own pages:
- British Army Jobs — SAS Reserve role, entry requirements, selection and locations
- British Army — UK Special Forces Reserve overview and recruiting contact
- British Army — 21 and 23 Special Air Service Reserve
- Soldier magazine (October 2025) — SAS Reserve recruiting feature
Checked 15 October 2026. The Army Jobs listing and the October 2025 Soldier article use different age wording — ask the recruiting unit rather than picking the convenient figure.
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What the stages are, what I was training to before I applied, and how I'd build the twelve weeks before a selection weekend. Written from my own application, free, no pitch.