This paper presents a computational evolutionary game model to study and understand fraud dynamics in the consumption tax system. Players are cooperators if they correctly declare their value added tax (VAT), and are defectors otherwise. Each player's payoff is influenced by the amount evaded and the subjective probability of being inspected by tax authorities. Since transactions between companies must be declared by both the buyer and seller, a strategy adopted by one influences the other?s payoff. We study the model with a wellmixed population and different scalefree networks. Model parameters were calibrated using real-world data of VAT declarations by businesses registered in the Canary Islands region of Spain. We analyzed several scenarios of audit probabilities for high and low transactions and their prevalence in the population, as well as social rewards and penalties to find the most efficient policy to increase the proportion of cooperators. Two major insights were found. First, increasing the subjective audit probability for low transactions is more efficient than increasing this probability for high transactions. Second, favoring social rewards for cooperators or alternative penalties for defectors can be effective policies, but their success depends on the distribution of the audit probability for low and high transactions.

中文翻译：

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理解消费税欺诈行为的演化博弈模型[研究前沿]

本文提出了一种计算进化博弈模型，以研究和理解消费税系统中的欺诈动态。如果玩家正确申报自己的增值税（VAT），他们就是合作者，否则就是叛逃者。每个参与者的收益受逃税金额和税务机关检查的主观概率的影响。由于公司之间的交易必须由买卖双方共同宣布，因此一个人采用的策略会影响另一个人的收益。我们研究了具有良好混合人口和不同无标度网络的模型。模型参数由西班牙加那利群岛地区注册的企业使用增值税申报的真实数据进行校准。我们分析了高低交易的审计概率的几种情况及其在人群中的普遍性，以及社会奖励和惩罚，以找到最有效的政策来增加合作者的比例。发现了两个主要见解。首先，增加低交易量的主观审计概率要比增加高交易量的主观审计效率更高。第二，偏向合作者的社会奖励或背叛者的其他惩罚可能是有效的政策，但其成功取决于低和高交易的审计概率的分布。