Does this count as term-time for the purpose of authorised work?
The Home Office have not confirmed this in guidance, however there is no reason to believe that this period will not continue to count as term-time for the purpose of authorised work. Students should be able to continue to undertake their authorised work as long as it is safe for them to do so and until the Home Office publish clear guidance to the contrary.
Tier 4 students often have limited work permission during term-time. Although colleges and universities are closing, this does not automatically mean that UKVI will accept that we are in a vacation period, allowing full-time work.
UKVI has confirmed that Tier 4 Students who work as Doctors, Nurses or Paramedics for the NHS can work without any limit on the number of hours.
There has been no similar announcement regarding Tier 4 Students employed in other roles. Unless clear UKVI guidance is given to confirm that students in other areas of work may currently work full-time, you should continue to work within any existing restrictions.