訊息不對稱,最適稅率與經濟成長

Asymmetric information,optimal tax and economic growth

王文程(Wang-Wen Cheng)

指導教授 ： 洪福聲

國立臺北大學/社會科學學院/經濟學系/碩士(2010年)

摘要

本文以Ho and Wang (2005) 的資本市場資訊不對稱模型為基礎，進一步考慮勞動市場也面臨資訊不對稱問題，探討當資本與勞動市場同時存在資訊不對稱的情況下，政府的最適財政政策為何？此外，我們也分別探討當勞動市場及資本市場資訊不對稱程度加深時，最適最適財政政策又會如何變動？對於經濟成長的影響又為何？

Barro (1990)發現，若資本市場沒資訊不對稱，則最適稅率等於公共資本的產出彈性。類似於Ho and Wang (2005)，納入資本市場資訊不對稱後，稅率增加會使高風險類型的借款者更有誘因偽裝成低風險類型的借款者，故貸款者必須要提高監督的機率，以防止高風險借款者假裝成低風險借款者。由於監督會浪費資源而不利於經濟成長，故最適稅率應該低於公共資本的產出彈性。本文納入勞動市場資訊不對稱後發現，最適稅率可能高於公共資本的產出彈性，也可能低於公共資本的產出彈性。主要原因為納入勞動市場資訊不對稱後，所得稅率增加對於經濟成長的影響會多了兩個不同方向的效果。一個由於勞動市場具資訊不對稱，使得勞動者選擇正式部門就業需付出搜尋成本，故資本市場上的可貸資金會減少，此時所得稅率增加會更加的扭曲私部門的資源分配，不利經濟成長，所以最適稅率會減少。另一個是所得稅率增加時，低能力勞動者進入正式部門就業的預期報酬會減少，表示低能力勞動者較沒有誘因進入正式部門就業，隱含失業率可以降低。失業率下降可以增加資本市場的資金供給，借款者進行的投資計劃金額也會增加，促進資本累積數量，有利經濟成長，所以最適稅率會增加。我們也進行比較靜態分析。

關鍵字

經濟成長 ； 資訊不對稱 ； 最適稅率 ； 失業

並列摘要

Based on Ho and Wang’s (2005) model, this paper examines the optimal fiscal policy by considering a framework that both labor and capital markets are subject to asymmetric information. We also examine the effects of an increase in the severity of asymmetric information in both markets on the optimal fiscal policy and economic growth.

Without the presence of asymmetric information in capital market, Barro (1990) has found that the optimal tax rate is equal to the output elasticity of public capital. Similar to Ho and Wang (2005), an increase in the tax rate in the presence of asymmetric information in capital market will induce high-risk borrowers to pretend as low-risk ones. To deter this under the separating equilibrium, lenders must raise screening probability. Since screening is costly, taxation creates additional distortion to the economy compared with Barro (1990). Thus, the optimal tx rate should be less than the output elasticity of public capital. By adding asymmetric information into labor market, we find that taxation creates two effects. First, employees must pay a search cost with the presence of asymmetric information in labor market. This implies that supply of loans in capital market decreases, which has adverse effect on capital investment and growth. Second, under asymmetric information, unemployment arises as a mean to separate labors with different ability. As the tax rate increases reduces the after-tax wage rate, which will deter low ability labors searching job in the formal market. This implies that the equilibrium unemployment can decrease. The lower unemployment rate will increase loan supply, which is beneficial capital investment and growth. We also offer some comparative analyses.

並列關鍵字

Economic growth ； Asymmetric information ； Optimal tax rate ； Unemployment

參考文獻

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