To my knowledge, we have not looked into exactly how much money the government is losing as a result of web giants. However, we have considered a tax on revenue above a certain threshold for technology firms, namely, the web giants. We don't really need to name names; we know who they are.
For example, we considered the effect that a 3% tax on companies earning revenue over a certain threshold would have. I do not remember exactly how much revenue that tax would generate, but Ms. Yan might be able to tell you after I answer the second part of your question.
We also considered how much money could be generated by a wealth tax. Unfortunately, I do not remember those amounts either. Once again, Ms. Yan might have a better memory than I do. However, the important thing is to have control measures. When people see a wealth tax coming, we know that they will quickly do what it takes to avoid paying that tax. The important thing to consider when imposing a wealth tax is the way it is designed and the way we go about it. We need to think carefully about the exemptions we have in mind and we need to have a proper structure in place for applying the tax.
Perhaps Ms. Yan could round out my answer by talking about the amounts that could be generated by imposing a tax on web giants and a wealth tax.