What a CAS actually is, who needs one, and how to get it
Almost everyone calls it a CAS letter. It is not a letter — it is a reference number your university issues after an unconditional offer, and you must apply for your visa within 6 months of receiving it.
It is a number, not a letter
The phrase "CAS letter" is everywhere, and it is the first thing to unlearn. A Confirmation of Acceptance for Studies is a reference number. Your education provider generates it and sends it to you once they have offered you a place, and you type that number into your visa application. There is no certificate to print and nothing to take to an appointment.
What the number represents is the important part: it is your provider telling the Home Office, on the record, that you hold an unconditional offer on a course with a licensed student sponsor. A conditional offer is not enough. Until every condition is met, no CAS is issued.
The six-month clock starts the day it is issued. GOV.UK is unambiguous: you must apply for your visa within 6 months of receiving your CAS. The same limit applies if you are extending or switching inside the UK. Miss it and the number is dead — you go back to your provider and ask for a new one, which they are under no obligation to give quickly.
Who needs one
Anyone applying for a Student visa needs a CAS, whether they are applying from outside the UK, extending an existing Student visa, or switching to one from another route. It is listed among the documents you must provide, alongside your passport. There is one unusual addition: you can also get a CAS if you are applying to work as a student union sabbatical officer.
Who does not
This is the part that saves people money, and it is why this page sits on a site about travel authorisations rather than degrees.
If your course lasts six months or less, you are not on the Student route at all. You can study as a Standard Visitor — and if your nationality qualifies for an ETA, that means a £20 authorisation rather than a £558 visa application. No CAS, no financial evidence, no sponsor. Short language courses, summer schools and executive programmes very often fall here, and people apply for a Student visa they never needed.
You also do not need one if you have settled or pre-settled status under the EU Settlement Scheme, because you do not need a visa at all.
How to get one
You cannot apply for a CAS. Only a licensed sponsor can issue one, and the sequence is fixed:
- Apply to the course and receive an offer.
- Meet every condition — grades, English language, deposit — so the offer becomes unconditional.
- The provider issues the CAS and sends you the reference number.
- You apply for the visa, quoting that number, within six months.
Two things commonly delay step three. Providers usually want a deposit against the course fee before issuing, and if you are studying or researching a sensitive subject at RQF level 7 or above you may need an ATAS certificate first. Neither is a formality; both take time you should budget for.
Check the number before you rely on it
Your CAS carries the course fee you are expected to pay, and that figure drives your financial evidence — you need the fee for one academic year of up to nine months, plus £1,529 a month for London or £1,171 outside it. If you are boarding at a residential independent school, the boarding fee on the CAS replaces the living-costs figure.
If the fee on the CAS is wrong, your money calculation is wrong, and a refusal on financial grounds is one of the easiest and most expensive ways to lose an application. Read the details before you submit anything.
A CAS is only as good as the sponsor behind it
This is worth understanding before you pay anyone a deposit. A CAS is only valid from an institution on the Home Office's register of licensed student sponsors, which is published and updated constantly — the version current as this was written was updated on 4 September 2026. You can look your provider up yourself, and you should.
The bar for staying on that register rose sharply on 4 June 2026. Institutions are measured on three metrics, and all three were tightened at once: visa refusal rate must now stay below 5% (it was 10%), course enrolment must reach 95% (was 90%), and course completion must reach 90% (was 85%). From summer 2027 a traffic-light rating will make the results public. Institutions rated red face limits on how many international students they may recruit, must fund a twelve-month action plan, and can lose the right to recruit internationally altogether if they do not improve.
The Home Office has also applied what it calls a visa brake on study visas for nationals of Afghanistan, Cameroon, Myanmar and Sudan.
None of that is a reason for alarm if you are going to an established university. It is a reason to check the register rather than trust a recruitment agent, and to be wary of any provider promising a CAS before you have an unconditional offer.
Checked against the official sources below on 5 September 2026.