The complex rules for claiming tax relief on travel and subsistence expenditure are explained by HMRC in booklet, 490 Employee Travel. Travel and subsistence expenditure incurred by or on behalf of employees can give rise to many difficulties. If HMRC find a problem, it is often several years after the event and they will generally look to collect any additional tax due from the employer, rather than the employee. So, a good understanding of the rules and watertight procedures are vital in avoiding expensive problems with HMRC.