He has an educational background in engineering, and has worked in various capacities in the civil service since 1987.

Tam has a Bachelor of Science degree in engineering from the University of Hong Kong.

Tam has served in various bureaus and departments including the Central Policy Unit, the former Constitutional Affairs Bureau, the Office of the Financial Secretary, the Chief Executive's Office, the Hong Kong Economic and Trade Office in Geneva, Information Services Department and the Home Affairs Bureau.

[2] His meteoric rise from undersecretary (D3 rank) to the director of the Chief Executive's Office (above D8 rank) in less than two years was a rarity and radical departure from normal civil service promotion.

In August 2018 he became executive director, corporate affairs of the Hong Kong Jockey Club.