One-way Permit

A People's Republic of China Permit for Proceeding to Hong Kong and Macao (Chinese: 中华人民共和国前往港澳通行证) or One-way Permit (Chinese: 单程证) is a document issued by the People's Republic of China allowing residents of mainland China to leave the mainland permanently to settle in Hong Kong or Macau.

The travel restriction was needed to prevent large volumes of people coming to Hong Kong or Macau and preventing illegal immigration.

Although the permit is specifically for the purpose of family reunion, not for general immigration, the scheme is controversial. Hong Kong currently has a quota of 150 people per day and the waiting time for spouses is currently 4 years. Journalist Ching Cheong alleges that the scheme, whose beneficiaries are at the sole discretion of the PRC government and outside of the vetting procedures of the Hong Kong Immigration Department, is an infiltration mechanism by spies and friends of the regime into Hong Kong; those that are not filled by spies become a graft mechanism for officials. Martin Lee said that the policy is part of the CPC's strategy of long-run "Tibetisation" of Hong Kong, aimed at marginalising Hong Kong people and their core values over time.

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Wikipedia