What are some tax types and bases that are currently adopted by other countries outside of Hong Kong? What are the reasons that these tax type or base should be or should not be introduced in Hong Kong? Please follow the following format:
1. Why it should be introduced/ not introduced
2. Reasons for the certain type of tax base
3. Estimated result and expectation once this base has been introduced
4. Proposed procedure for the tax base
5. potential problems in introducing the tax base