Does Hong Kong have a tax treaty with Mainland China and Malaysia?

Hong Kong's DTAs mainly allocate taxing rights over income between Hong Kong and the other jurisdiction and provide relief from double tax.

Mainland China. The Inland Revenue Department (IRD) notes the Arrangement between the Mainland and Hong Kong for the avoidance of double taxation (signed 21 August 2006); it is called an Arrangement, not a treaty, but works like one.

Malaysia. The Hong Kong-Malaysia DTA was signed on 25 April 2012, entered into force on 28 December 2012 and has effect in Hong Kong from the year of assessment 2013/14. The IRD marks it as modified by the Multilateral Instrument (MLI) and provides a synthesised text.

How to use a treaty

1. Check that the other country's treaty is in effect and which taxes it covers.
2. Get a Certificate of Resident Status from the IRD if the foreign authority asks for one.
3. Claim the reduced rate or exemption under the foreign country's procedures; the treaty text and local law decide the rate, not this answer.

Unilateral relief. The profits tax return also includes an item for foreign tax paid claimed as a unilateral tax credit.

The IRD page lists the current treaties and their effective dates, and the list is updated as new agreements are signed.