In late July, Beijing set an October 22 deadline for the declaration of offshore trust income, with a ⁠tax of 20% to be imposed on such profits, triggering a scramble among wealthy Chinese individuals to tot up liabilities.

Boston Consulting Group estimates China's offshore wealth at about $1.7 trillion, and offshore trusts have gained ​popularity in recent years as a tool for top shareholders of overseas-listed Chinese companies to park wealth outside the country.

China's State Taxation Administration has ordered employees to chase up those liable for offshore trust tax, ​working from a list drawn from the Hurun wealth rankings, corporate filings and other public information, three people said.