多重均衡视角下的中国外债风险与非线性资本流动税的应用

China's Foreign Debt Risk and the Application of Nonlinear Capital Flow Tax from the Perspective of Multiple Equilibrium

开放经济条件下,当一国市场主体对外借债时,除最优外债水平能够促进经济处于稳态均衡外,还可能存在更低外债水平导致经济处于危机均衡状态,产生除最优稳态均衡外的多重均衡现象。本文基于多重均衡视角,通过构建产出抵押模型,分析一国市场主体以产出为抵押物对外借债的风险,并进一步将产出抵押模型拓展为资产抵押模型,分析金融机构以不同类型资产为抵押物对外借债的风险。为消除多重均衡可能引发的金融危机,本文纳入非线性资本流动税工具(根据以不同抵押物对外借债时的规模累进征税),模拟中国总体外债与金融机构外债的最优资本流动税率。研究结果表明:第一,中国当前总体外债水平不会引起由多重均衡导致的金融危机;国内可贸易品与不可贸易品替代弹性越小,总体外债水平引发金融危机的可能性越低,最优资本流动税率越低,可采用补贴型资本流动税率鼓励外债资金流入。第二,中国金融机构对外负债率低于最大对外负债率,但基于金融加速器机制,应通过约束型资本流动税率进行管理。第三,中国当前金融机构外债水平远低于中国人民银行宏观审慎评估体系(MPA)中跨境融资风险加权余额上限;金融机构对外借债的抵押资产流动性越大,最优资本流动税率越高。

Summary:In an open economy,when an economy borrows externally,in addition to the optimal level of foreign debt to promote the economy to a steady-state equilibrium,there may be other lower levels of foreign debt to make economy in a state of crisis equilibrium,resulting"'multiple equilibria"phenomenon in addition to the optimal steady-state equilibrium.Based on the perspective of multiple equilibria,this paper analyzes the risk of a country's external borrowing with output as collateral by constructing an output collateral model.Furthermore,it extends the output collateral model to an asset collateral model to analyze the risk of financial institutions'external borrowing with different types of assets as collateral.To eliminate financial crises induced by multiple equilibria,this paper incorporates a nonlinear capital flow tax instrument(progressive taxation based on the size of foreign debt when borrowing against different collateral).This instrument is used to simulate the optimal capital flow tax rate for China's overall foreign debt and the foreign debt of financial institutions.The results indicate that:Firstly,China's overallforeign debt does not trigger any financial crisis due to multiple equilibria.The lower the elasticity of substitution between domestic tradable and non-tradable goods,the lower the possibility of financial risk arising from overall foreign debt.This results in a lower optimal capital flow tax rate.Currently,the subsidized capital flow tax rate should be adopted to encourage the inflow of foreign debt funds.Secondly,the foreign debt ratio of Chinese financial institutions is lower than the maximum foreign debt ratio alert value.However,based on the financial accelerator mechanism,the foreign debt of financial institutions should be managed through the constrained capital flow tax rate at present.Thirdly,the current foreign debt of Chinese financial institutions is far below the upper limit of the risk-weighted balance of cross-border financing of the Macro Prudential Assessment(MPA)system of the People's Bank of China.The optimal capital flow tax rate is higher when the liquidity of the collateral assets of financial institutions'external borrowing is greater.The policy recommendations of this paper are to continue promoting the opening-up policy and actively improving the reform of foreign debt facilitation.This will stimulate the growing demand for external financing of different market entities and expand the space for foreign debt of financial institutions.It is also essential to improve the macro-prudential management of China's cross-border financing.Furthermore,the paper suggests gradually implementing the nonlinear dynamic adjustment of capital flow tax for risk prevention.This should be based on the scale of foreign loans of different entities with different objects as collateral as the main variable.