Visa Letters become obsolete but are replaced by CAS Statement - from 22 February 2010 it will be mandatory for all potential students applying for leave from inside or outside the United Kingdom to use a Confirmation of Acceptance for Studies (CAS) in their application. Applications that do not contain a CAS after the 22 February will fall for refusal. Changes to sponsor guidance, migrant guidance and application forms are available on the UK Border Agency website from Monday 22 February from the following links: Tier 4 migrant guidance and application form: Adult Students: http://ukba.homeoffice.gov.uk/studyingintheuk/adult-students/