In the perspective of neoclassical economics, the concept of taxation has undergone profound changes. The effective tax rate has become a key factor guiding capital flow, prompting tax authorities to focus more on those who cannot "move away." Compared with top wealthy individuals and large capital that can easily achieve cross-border flow, taxing relatively fixed tax bases such as land, real estate, and domestic consumption seems to be a more stable and efficient choice. After all, in the context of increasing global capital mobility, excessively high effective tax rates can easily lead to capital outflow, eroding the tax base, and ultimately harming economic development. Therefore, in order to maintain tax revenue and promote economic vitality, maintaining a relatively low effective tax rate to attract domestic and foreign capital inflow becomes a rational choice.

At the same time, the attractiveness of low effective tax rates to capital also contains the potential to expand sovereign credit. The modern monetary system provides the government with space for credit expansion. As long as the speed of economic growth can surpass the speed of debt accumulation, raising the debt ceiling through credit expansion, or even using seigniorage and other means, seems to provide a solution to the debt problem. Of course, whether this model can continue to operate depends on whether economic growth is strong and sustainable.

Historically, the fiscal difficulties of the Ming Dynasty, to a certain extent, confirm the above views. In an era when globalization had not yet deeply developed and capital mobility was limited, the Ming Dynasty found it difficult to effectively absorb external capital by lowering tax rates. Coupled with the constraints of the precious metal standard system, it lacked the credit expansion and monetary policy tools possessed by modern economies. In the context of low effective tax rates, narrow tax bases, and limited fiscal revenue, the Ming Dynasty eventually fell into an inextricable fiscal crisis.

Therefore, to some extent, there are profound internal connections between the effective tax rate, capital flow, sovereign credit, and debt. In the context of globalization, tax authorities need to carefully weigh the setting of effective tax rates, ensure fiscal revenue, avoid capital outflow, and rationally use credit expansion tools to cope with debt challenges, ultimately promoting long-term healthy economic development.