OECD與歐洲委員會於2010年修訂《多邊税收徵管互助公約》鼓勵世界各國共同簽訂以建立國 際税收徵管之合作原則與標準以來，目前已有100多個國家簽署，面對全球反避税查税趨勢，未來 企業避税之隱匿成本將提高。惟囿於查税人力經費等限制，各國税捐機關實際上無法對所有納税人的 匿報資料進行全面清查；本文發現馬可夫鏈係指在已知當前與過去狀態下，未來轉換機率僅依賴當前 狀態；與過去事件無直接關係。由於代表性納税人選擇誠實繳税抑或逃漏税，係當事人當期之内生決 策變數，約當馬可夫鏈模型，爰此，本文主要以馬可夫鏈模型，計算核課期間内逃税人數以及税基侵 蝕金額大小。

Some dutiful people will undoubtedly pay what they owe, but many others will not. Tax authorities shall punish the tax evaders found to have violated the tax laws. OECD and the European Commission in 2010 to amend the "multilateral tax collection and mutual assistance Convention" to encourage countries around the world signed to establish international tax collection and standards of cooperation. But limited to inspection funds and manpower constraints, tax authorities can not check whether the taxpayer is honest to declare the real income. So far, there seem no literature to estimate the proportion of taxpayers in a country who will evade taxes. In this paper, we try to establish the model of taxpayers' possible behavior by Markov chain and calculate the proportion of taxpayers in a country within a certain period will choose to pay the tax honestly or choose tax evasion. So as to serve as a reference for a government to predict the extent of tax erosion.