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, a 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 a Consultant role, there will be a brief break after retirement before commencing the consultant role, which I also underwent for two years.