If you are, like I am, interested in passports and travel documents, you'll find China, HK, Macau, and Taiwan one of the most fascinating cases of nationality and immigration laws. What's the maximum number of passports one can obtain from these four jurisdictions?

Excluding non-passport travel docs (HK Doc of Identity for Visa Purposes & PRC Travel Doc)—

PRC issues Chinese passports for mainlanders and HK/Macau SAR pps;

Taiwan issues ROC pps;

UK issues BN(O) pps to pre-'97 holders;

Portugal issues Portuguese pps to pre-'99 holders.

HK & Macau permanent residencies are not mutually exclusive, so theoretically one qualifies for 4 passports. Before 1997/99 Taipei allowed ethnic Chinese HK/Macau residents to obtain ROC passports under certain conditions, so that makes it 5…

If you go to Macau you'll find many people who hold both ROC and Macau passports, because Taiwan was once the top college dest. for Macau's high school graduates, and it used to offer a 'pathway to citizenship' (not really - Macau citizens were legally considered ROC nationals)

It's legal in the PRC for Taiwanese citizens to obtain PRC passports in two scenarios: 1) by obtaining hukou in the PRC; 2) by joining a Chinese tour group to Russia, crossing the border by land. In the former case, the individual's household reg. in Taiwan can be revoked…

But I wonder if that means the person would still qualify for a ROC passport for overseas nationals (無戶籍國民). Anyhow I don't know anyone who has tried this.

If one counts all the non-passport border crossing documents, then it gets even more interesting. There's the PRC travel doc (旅行证), PRC-issued mainland permit for SAR/TW residents (回乡证, 台胞证), PRC-issued HK/Macau/TW permit for mainlanders (港澳通行证, 单/双程证, 大通证)…

I know that mainland immigrants to Hong Kong can, in practice, keep both PRC and HK SAR passports. When @zuola got his Taiwanese passport he also wasn't asked to surrender his PRC one. https://twitter.com/zuola/status/1210367684908478464