What Is a CAS Letter? UK Student Visa Guide
If you've received an offer from a UK university and started looking into your student visa, you've probably run into the term CAS letter - and quickly realised you can't apply for your visa without one. Here's exactly what it is, how you get it, and the mistakes that trip people...
1. What Is a CAS Letter, Exactly?
CAS stands for Confirmation of Acceptance for Studies. It's an electronic document - not a physical letter - issued directly by your UK university once you've accepted an unconditional offer and confirmed you intend to study there. Every CAS carries a unique reference number that's tied specifically to you, your course, and that university.
Think of it as your university formally vouching for you to the UK government: it confirms who you are, what you're studying, and that a genuine place is waiting for you.
2. Why You Need a CAS Letter for Your UK Student Visa
You cannot submit a UK student visa (Student Route) application without a valid CAS number. It's one of the core pieces of evidence the Home Office checks under the points-based immigration system, alongside your financial evidence and English language proof. Without it, there's no application to make - it's the first hard requirement, not an optional extra.
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3. How to Get Your CAS Letter
Accept your unconditional offer. Your university won't issue a CAS against a conditional offer - any outstanding conditions (final grades, English test results) need to be met first.
Submit the documents your university asks for. Typically your passport, academic transcripts and certificates, English language test results, and evidence you can cover your fees and living costs.
Confirm your intention to study. Most universities ask for a deposit or a written confirmation before they'll generate the CAS - check what your specific offer letter says.
Wait for your CAS to be issued. Universities typically issue it within a few weeks of receiving everything they need - see the timing section below.
Use your CAS number in your visa application. You'll enter it directly into the online Student visa form on GOV.UK.
4. What Information Does a CAS Letter Contain?
Your CAS record includes:
Your unique CAS reference number
Your full name and date of birth, matched against your passport
The course you're enrolled on, its level, and start/end dates
Confirmation of your English language proficiency
Your tuition fees, and how much (if anything) you've already paid
Whether you need to show maintenance (living cost) funds, and how much
Everything on it needs to match your passport and other documents exactly - a spelling mismatch between your CAS and your passport is one of the most common (and easily avoidable) causes of a delayed visa decision.
5. CAS Letter Processing Time
Most universities issue a CAS within roughly 1 to 3 weeks once they have every document they need from you - though this varies by institution and by how close you are to intake deadlines. It's worth applying and submitting your documents as early as possible; requests submitted close to a September intake often queue behind a much larger volume of applicants.
6. CAS Letter Validity: The 6-Month Window
A CAS is valid for 6 months from its issue date, and it can only be used once. If your visa application is refused, withdrawn, or you don't apply within that window, the same CAS can't be reused - your university will need to issue a new one. This is exactly why timing your CAS request against your intended visa application date matters.
7. Common CAS Letter Problems (and How to Avoid Them)
Name mismatches. Double-check your CAS shows your name exactly as it appears on your passport, including middle names.
Financial evidence gaps. If your CAS states you need to show maintenance funds, that money generally needs to have been in your (or your parent's/guardian's) account for a minimum consecutive period before you apply - check the current GOV.UK guidance for the exact window, as this detail has changed before.
Letting it expire. Don't request your CAS the moment you accept your offer if your visa application is still months away - request it once you're genuinely ready to apply.
Applying before it's issued. You can't start a Student visa application without the CAS number in hand - there's no way to "hold a place" in the queue without it.
8. What Happens After You Have Your CAS?
Once your CAS is issued, the next steps are your Student visa application itself: completing the online form on GOV.UK, paying the visa fee and Immigration Health Surcharge, booking a biometric appointment, and - depending on your country of application - possibly a Tuberculosis (TB) test certificate. Processing times for the visa decision itself are separate from CAS issuance, so build in buffer time before your course start date.
Key Things to Remember
You need an unconditional offer before a university will issue your CAS.
A CAS is valid for 6 months and can only be used once.
Every detail on it must match your passport exactly.
Request it with enough lead time before your intended visa application - not the moment you accept your offer.
Typically 1–3 weeks once your university has received every document it needs from you, though this varies by institution and by how close you are to a busy intake period.
It becomes unusable. Your university will need to issue a new one before you can submit your visa application - always check the 6-month window against your planned application date.
No, it's a required piece of evidence, not a guarantee. Your visa decision also depends on your financial evidence, English proficiency, and the accuracy of your application as a whole.
You can hold offers from multiple universities, but you'll only request a CAS from the one you've decided to actually accept and study at - request it once you're certain, since it's tied to that specific course and institution.
