Upon retiring, Tan devoted much of his time to his hobbies, which included reading (at the time of his death, he had accumulated 5,000 books), cricket, and the study of military history, with a special focus on the Middle East. He also wrote a column for "The Star", which also published a column by the Tunku, until the government tightened its regulations on the press in 1988. Tan later alleged that he had wanted to write soon after his retirement, but was prevented from doing so because he was formerly in the opposition.