He moved rapidly. First, he promoted Confucian orthodoxy and reversed what he saw as his father's laxness by cracking down on unorthodox sects and by decapitating an anti-Manchu writer his father had pardoned. In 1723 he outlawed Christianity and expelled Christian missionaries, though some were allowed to remain in the capital. Next, he moved to control the government. He expanded his father's system of Palace Memorials which brought frank and detailed reports on local conditions directly to the throne without being intercepted by the bureaucracy, and created a small Grand Council of personal advisors which eventually grew into the emperor's de facto cabinet for the rest of the dynasty. He shrewdly filled key positions with Manchu and Han Chinese officials who depended on his patronage. When he began to realize that the financial crisis was even greater than he had thought, Yongzheng rejected his father's lenient approach to local landowning elites and mounted a campaign to enforce collection of the land tax. The increased revenues were to be used for "money to nourish honesty" among local officials and for local irrigation, schools, roads, and charity. Although these reforms were effective in the north, in the south and lower Yangzi valley, where Kangxi had wooed the elites, there were long established networks of officials and landowners. Yongzheng dispatched experienced Manchu commissioners to penetrate the thickets of falsified land registers and coded account books, but they were met with tricks, passivity, and even violence. The fiscal crisis persisted.
Is there an answer to this question (If it cannot be answered, say "unanswerable"): When did Yongzheng ban christianity?
1723