All About the CAS Letter For UK Student Visa : Requirements, Processing Time and What It Contains

The CAS letter is one of those UK student visa requirements that students hear about but often don’t fully understand until they need it.

It’s not a document you apply for yourself, it doesn’t come from the Home Office, and you can’t move forward with your student visa application without it.

Understanding exactly what it is, where it comes from, and what happens if there are errors in it saves real time and stress.

What CAS Actually Stands For

CAS stands for Confirmation of Acceptance for Studies. Despite the name, it’s not a letter in the traditional sense – it’s a unique reference number, fourteen characters long, generated by your UK university through the Home Office’s Sponsorship Management System.

When people say “CAS letter,” they usually mean the full document your university sends you that contains the CAS number along with all the details about your course, fees, and personal information.

The CAS number itself is what you enter into your online student visa application. The accompanying document with the details is what you need to cross-check carefully before submitting your visa.

Who Issues the CAS

The CAS is issued by your UK university or college – specifically, it can only be issued by institutions that hold a valid Student Route sponsor licence from the Home Office.

This is a significant point : if your university doesn’t have a current sponsor licence, it cannot issue a CAS, and you cannot get a student visa to study there.

Before you accept any university offer, it’s worth confirming that the institution appears on the Home Office’s register of licensed sponsors, which is publicly available on gov.uk.

Reputable universities all maintain this licence as a matter of course, but it’s worth checking for any institution you’re unsure about.

What the CAS Contains

The CAS number and accompanying document include specific information about you and your course that the Home Office uses to verify your visa application. The standard information includes:

Your full name exactly as it appears in your passport. Your date of birth. Your nationality. Your passport number. The name and address of the sponsoring institution. The course name. The course level. The course start date and end date. The total course fees. The amount of fees you’ve already paid, if any. Whether your English language proficiency has been assessed by the institution. Your academic qualifications that were used in your admission decision.

The key thing to check when you receive the CAS document: every single detail must match your passport and your application exactly.

Name spelling, date of birth, passport number – these are the fields where errors cause the most problems. An error in the CAS that doesn’t match your passport means your visa application is likely to be rejected or delayed while corrections are made.

When the University Assigns Your CAS

UK universities don’t issue your CAS immediately when they send you an offer. The sequence is:

You receive an offer from the university. You accept the offer and meet any conditions (academic results, English language scores, etc.). You receive an unconditional offer. You confirm your enrollment by paying the required deposit. The university then assigns your CAS, usually within a few weeks of deposit payment.

Universities have a window during which they can assign CAS numbers – typically several months before the course start date. Most universities begin assigning CAS numbers to confirmed students around four to six months before the course starts, though this varies.

Some universities ask you to formally request your CAS through their online student portal. Others issue it automatically once you’ve confirmed enrollment. If your course start date is approaching and you haven’t received your CAS, contact your university’s international student admissions team directly.

Processing Time : How Long Does It Take?

There’s no fixed timeframe for CAS issuance – it’s at the university’s discretion, within the limits set by the Home Office.

In practice, after you’ve confirmed your enrollment and paid your deposit, most universities take between one and four weeks to issue your CAS number and accompanying document. Some universities are faster, particularly those with high volumes of international students who are experienced at processing CAS assignments efficiently.

The visa application timeline should account for CAS processing. The recommended sequence:

Receive unconditional offer. Pay enrollment deposit. Wait for CAS to be assigned (one to four weeks typically). Receive CAS document. Check all details against your passport. Submit student visa application (which can be submitted up to six months before your course start date). Wait for visa decision (typically two to four weeks for standard processing).

If your course starts in September, most advisors recommend aiming to have your CAS by June or July at the latest to give yourself comfortable processing time for the visa.

CAS Validity : How Long Is It Valid

A CAS is valid for six months from the date it’s assigned. Your visa application must be submitted within this six-month window. If you don’t submit within six months, the CAS expires and the university must assign you a new one.

This matters most for students whose plans change or who receive their CAS very early. If you receive your CAS in March for a September course start, and you wait until October to apply for the visa (for whatever reason), the CAS will have expired and you’ll need a new one.

Most students submit their visa application within a few weeks of receiving the CAS, which makes the six-month validity a non-issue. But it’s worth knowing in case of delays.

What Happens If There’s an Error on the CAS

Errors on CAS documents do happen – typically mismatched name spellings, incorrect dates, or wrong course codes. The process for fixing them is straightforward but takes time.

Contact your university’s international admissions office as soon as you spot an error. They will need to withdraw the incorrect CAS and assign a corrected one. This process can take days to weeks depending on the university’s administrative processes.

Do not submit your visa application with a CAS you believe contains errors. The Home Office will match the CAS details against your passport and any discrepancy will flag your application.

CAS and the Visa Application

When you submit your UK Student Visa application online through gov.uk, you enter your CAS number as part of the application form. The system pulls the course and institution details automatically from the CAS database.

You don’t need to upload the CAS letter itself as a separate document – the number is what matters. However, you should keep the CAS document and all the details it contains because:

You may be asked about specific details from the CAS if your visa application requires additional review. It serves as your record of what the Home Office was told about your course and enrollment. You’ll need it when you contact your university about any post-visa enrollment queries.

What a Typical CAS Document Looks Like

Universities vary in how they format their CAS documents, but most include a reference block at the top with the CAS number in bold or highlighted, followed by sections for:

Student personal details (matching passport information). Sponsor details (the university’s licence number and contact). Course details (name, level, dates).

Financial information (total fees, fees paid). English language assessment details (how the institution verified your proficiency). Declaration by the institution.

The document is typically two to three pages. Some universities send it as a PDF by email; others make it available through the student portal. A few send a physical copy along with other enrollment documentation.

Practical Things to Check When You Receive Your CAS

Check your name spelling first. If your passport shows “Ramachandran Subramaniam” and your CAS shows “Ramahandran Subramanian” – even minor variations – this needs to be corrected.

Check your date of birth. Day and month transpositions are a common error.

Check your passport number. This should exactly match the passport you’ll be using for the visa application.

Check the course name and start date. If you’re enrolled in “MSc Data Science” and the CAS says “MSc Data Analytics,” or if the start date is off by a week, contact the university.

Check the fee amount. The total course fee should match what your offer letter stated. If you’ve already paid a deposit, the CAS should reflect fees paid.

One Common Misunderstanding Worth Clarifying

Some students believe the CAS is proof of a visa or some kind of entry permission. It isn’t. The CAS is purely an internal document between your university and the Home Office that confirms the university is sponsoring your student visa application.

The visa itself is a separate approval from UKVI, and you cannot travel to the UK to study on a CAS alone.

You need both: the CAS from the university, and the student visa from UKVI. The CAS enables the visa application; the visa enables entry.