In L&T, where I worked for 33 years and retired, one message goes to the HOD one year in advance to facilitate succession planning. Then six months before the due date, formal retirement letter, with formats for NOCs from various departments, forms for signing of PF Settlement, permanent address post retirement etc are sent by the HR Department. On the last date, there will be a farewell party in a formal manner. For Consultant role, there will be a brief break after retirement for commencing consultant role, which too I underwent for two years.