He later served as a secretary to the military governor (Jiedushi) of Jingxuan Circuit (涇原, headquartered in modern Pingliang, Gansu), and then returned to Chang'an to serve as an imperial censor with the title Shiyushi (侍御史) then Xingbu Yuanwailang (刑部員外郎), a low-level official at the ministry of justice (刑部, Xingbu).
The next year, he got promoted to the prefect of Rao Prefecture (饒州, in modern Shangrao, Jiangxi), and later returned to Chang'an to serve as Jianyi Daifu (諫議大夫), a high-level consultant; and then was made the deputy minister of civil service affairs (吏部侍郎, Libu Shilang).
Before he could arrive at Henan, there was a birthday for Emperor Dezong, and it was customary for the mayors of the special municipalities to offer horses as tributes.
Once he arrived at Henan, he governed the city without much fanfare, and rested the people by lowering taxes and increasing stipends.
When his subordinates worried for him that this would offend Han and the eunuchs, Zheng responded:[4] When generals are on campaigns, they often use that as the excuse to make demands.
[6] At that time, one of Emperor Dezong's close associates, Li Shi (李實) the Prince of Dao, was the mayor of Jingzhao Municipality (京兆, i.e., the Chang'an region), and Li was well known for being harsh in his tax collections in order to offer tributes to Emperor Dezong.
Where did your tributes come from?At that time, however, Li was trusted by Emperor Dezong, and therefore suffered no ill consequences from Zheng's investigation.
Emperor Shunzong made Zheng Xunyu the minister of civil service affairs (吏部尚書, Libu Shangshu) and still a chancellor.
At that time, Emperor Shunzong's close associate Wang Shuwen had become very powerful and was allied with Zheng's chancellor colleague Wei Zhiyi.