Dr Tan Thai Lian practises Geriatric Medicine with a special clinical interest in the different models of care that would benefit the frail older person.

He is currently the Divisional Chairperson, Division of Medicine at Woodlands Health. From 2007 to 2014, he was the Head of the Geriatric Medicine Department at Tan Tock Seng Hospital (TTSH), the Chairman of Division of Medicine (TTSH) from 2015 to 2018, and Assistant Chairman of the Medical Board (ACMB - the Deputy CMB equivalent, TTSH) from 2018 to 2019. He also served as the Clinical Director of Ren Ci Hospital for three years from 2010 to early 2013.

During his leadership tenure, Dr Tan implemented various system-level change, including setting up GEMS (Geriatric Evaluation Management and Subacute Care) units, conceptualising the first Delirium care unit in Singapore (Geriatric Monitoring Unit, GMU), implementing the Framework for the Inpatient Care of the Frail Elderly (FIFE), guiding the setting up of an acute medical unit (Acute Internal Medicine Service, AIMS), and leading the development of Complex Care Clinic. He also chaired various hospital-level committees, including SOC (Specialist Outpatient Clinic) Steering Committee, Infectious Disease Outbreak Committee, and Bed Management Committee.