EIM32250 | Travel expenses: travel for necessary attendance: emergency call-out and stand-by: stand-by

From HM Revenue & Customs · Employment Income Manual

Section 338 ITEPA 2003

Even where an employee is on stand-by and can be called out at short notice he or she is not entitled to a deduction for the cost of a journey that is ordinary commuting. No deduction is due where an employee on stand-by has to travel to a permanent workplace, whether or not the travel is during ordinary working hours.