In general, any documents from outside of China must be certified and notarized regardless of if they come from a foreign government department or the litigant themselves. This includes divorce will statement, marriage certificate, identification documents, and power of attorney letter.
After being notarized, documents must be authenticated for legitimacy of seal and signature by the Chinese embassy or consulate located in that country. Once they are found to be authentic, they will be stamped. If a Chinese citizen in a foreign country needs a legal document to be used in Chinese court, they can do directly to the Chinese embassy or consulate for a direct notarization.
For notarization and certification in Hong Kong, it’s necessary to be notarized by a lwyer in the area that is designated by China’s Ministry of Justice. It will then be transferred to a Chinese legal service where the procedure becomes pretty simple from that point. Macao is similar to Hong Kong with the addition of notarization can be done directly through a non-lawyer notary.
In Taiwan, materials are notarized by the authorities in Taiwan and copies are sent to mainland China’s Notary Association for certification. The original official documents in Taiwan must be sent directly through the Strait Exchange Foundation.