A diplomatic clause allows to terminate the lease before its expiry at a fixed time (or times) or upon the occurrence of a specified event(s). These events, in general, are focused on employment. For example, you need to relocate to another part of the country (more than 50 KM away) or another country. Or you need to return to your home country for a job-related event. In these cases, you can get out of a contract. Most of the times one will only have to pay 2 months rent. Of course, proof must be provided in order to be able to appeal to this clause.
