Tai Yuan is an auxiliary concept in BaZi (Four Pillars of Destiny) astrology, referring to the Heavenly Stem and Earthly Branch of the month of conception. Tai Yuan represents one's innate endowment and maternal environmental influences; when analyzed together with the Four Pillars, it reveals the native's constitutional predisposition and early-life fortune. Tai Yuan, together with the Ming Gong (Destiny Palace), constitutes the auxiliary palaces in destiny analysis.
Method to determine Tai Yuan: advance the Heavenly Stem of the Month Pillar by one position, and advance the Earthly Branch of the Month Pillar by three positions; the resulting Stem-Branch combination is the Tai Yuan. For example, if the Month Pillar is Jia Zi, advancing the Stem yields Yi, and advancing the Branch three places from Zi yields Mao; thus, the Tai Yuan is Yi Mao.
Month Pillar: Jia Zi; Tai Yuan: Yi Mao. For a Jia Wood Day Master, Yi Mao represents Rob Wealth; this suggests a generally acceptable innate constitution but necessitates vigilance regarding health during childhood.