Zhengcai is the element controlled by the Day Master of opposite polarity — e.g. a 甲 (yang wood) day master "controls" 己 (yin earth) as Zhengcai. It represents stable, predictable wealth: salary, savings, real estate income, and money earned through diligent labor.
Healthy Zhengcai gives reliability with money, careful budgeting, and steady financial growth. In male charts it represents the legal wife. Excessive Zhengcai can be miserly or stuck in conventional thinking; too weak indicates financial scarcity or lack of structure around money.