Asking someone to be a reference after a long time

A former manager or colleague might be a good reference even if the last conversation was a while ago. Reaching out can still feel awkward, especially when there is an application deadline approaching. What information makes the request easy to answer? A reminder of the work done together, the type of role, and enough notice seems more considerate than simply adding a name to a form. Giving the person a comfortable way to decline also matters. A useful reference comes from someone willing and able to speak about the relevant work.