SPR moving to HK, package consultant

[Strong Eagle]

So if there is SPR residing overseas but receiving Singapore sourced salary, is he considered local tax resident and can enjoy lower taxes or he has to pay 15% non resident taxes?

It is not clear what you mean by "Singapore sourced salary".
If the salary is paid for work overseas, and this work is not incidental to employment in Singapore (e.g. business trips or overseas training are incidental, secondment is not), then it is not taxable in Singapore, regardless of where and how it is paid - merely being paid in Singapore does NOT make you tax-liable here (that is exactly the constellation I had before).

If it is incidental to Singapore employment, it is normally taxed at resident tax rates.
I believe it would be very difficult to construct a case where a PR has permanently left Singapore (and thus could be treated as non-resident for tax matters) but still receives income that is incidental to an employment here - but if you find such a case, please ask IRAS how it is treated.

To add to this... your income will be taxable in HK, and you must have a valid HK work permit. They are not going to let you just waltz in and work.