Students at an institution may decide to take courses at another institution, if space is limited in the same course at their own institution, or because a particular course is not offered at their own institution. They take these courses with the intention of transferring credit back to their home institution (the receiving institution).
At many institutions, it is standard practice for the student taking a course elsewhere to obtain a Letter of Permission (LOP), which confirms that the home institution is aware of the student's enrollment elsewhere and will accept the other institution's course for transfer credit. It is recommended that institutions only refuse requests for Letters of Permission where there are solid and justifiable reasons for doing so, based on the best interests of the student. Students may occasionally request retroactive LOPs for courses they have already taken elsewhere as visiting students; some institutions' policy is not to issue retroactive LOPs, on the basis that it is in the student's and institution's best interests to determine in advance