I am extending my visa to a DES visa, do I need a new ATAS?
You do not need to hold or apply for an Academic Technology Approval Certificate (ATAS) to cover your time spent on the Doctorate Extension Scheme. If, however, you are currently studying a course (or period of research) that requires an ATAS Clearance Certificate, and your course end date given on the CAS is postponed for a period of more than 3 calendar months, you must apply within 28 days of being notified of the change in course for a new ATAS Clearance Certificate to cover the rest of your time on that course.