C
ESA is paid fortnightly in arrears so I would expect one more payment to cover the period 16/12/ to 22/12.
If you have an End Date to your award then you will be reassessed at any time up to a year earlier. Although it is called a review you are still being assessed against the same criteria as when you originally applied, the only difference is that, in theory anyway, they should use the documentation from your previous assessments.
Gordon
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
