I always have a small mileage claim, never goes over 100 miles a month but recently I changed jobs within the company and will have slightly more miles due to there being a service industry subsidiary. I am based in admin at the group HQ about 7 miles away from the plant so everytime I have to go there its 14 miles on my expenses. However it happens that the plant just off the main road on my drive home and sometimes I just leave work early and call into the plant on my way home. Should I still be claiming mileage for this? I never bother cos I'd be going home anyway and only go about a quarter of a mile out of my way