Under changes to the Immigration Rules effective from 13 December 2012, absences of up to 180 days in each of the 12 month calendar periods of the 5 year qualifying period for continuous residence will be permitted for Tier 1 (General), Tier 2 and pre-points based system work routes e.g. work permits. These absences must be for a reason that is consistent with the person’s employment e.g. business trips, conferences, research collaborations, periods of annual leave – or for serious or compelling reasons such as the serious illness of a close relative.