He should be able to get a universal credit payment backdated because of illness
My son fell ill in September and was put into an induced coma. He was in hospital for two weeks and, as he was unable to work or start his planned masters degree, he applied for universal credit. A fortnight later, he asked if the payment could be backdated to the day of his hospital admission (7 September) when he first became eligible. His admission was exactly a month before he made his original application for the benefit to start on the 8 October.
Legislation allows it to be backdated by a month subject to certain conditions, including illness. This was initially agreed. The Department for Work and Pensions (DWP) then said it could only backdate for a month from when the request to backdate was made, not from when he originally applied. This means he has been underpaid 12 days of credit, amounting to £142.