由於借款利差為銀行重要的收入來源，但在制訂過程中可能受到不同因素的影響，本研究除探討企業信用風險對利差與利差變異的影響外，也說明不同的銀行與企業之往來關係在借款利差訂定中有否差異，使借款利差產生高低，抑或改變審件人員的主觀態度。 在借款利差的方面主要支持道德風險假說，即在資訊不對稱情況下銀行對於信用風險較高的借款企業給予較高的借款利差。其次，往來關係方面發現，民營非金控銀行和外資銀行依賴度較高之企業，會隨著依賴度的提高增加借款利差，但與公營和民營金控銀行往來較密切的企業，其借款利差較低。也發現銀行對於往來關係較佳(往來銀行家數較少)的企業會給予較低的借款利差。借款契約條件的討論不支持訊號發射假說，銀行傾向將擔保品視為降低道德風險的工具，藉由保證增加降低信用風險的承擔。 借款利差變動的探討中，主要支持人為主觀因素造成利差變動的概念：(1)銀行規模越大、授信人員較多，故借款利差加減碼部分難趨統一；(2)成本費用與變動的正向關係顯示增加的成本反映在人為因素影響的利差波動；(3)由於公營行庫薪資結構與放款績效連結較小，使授信人員無動機以人為方式壓低借款利差以求競爭，故較民營銀行在利差變動的程度較小。Since the loan Premium is an important source of income for the bank, but the processes are determined by different factors. This study exams how the corporate credit risk affect the loan premium and the discretion of loan premium, also shows that whether the different relationships between banks and enterprises changes the processes of loan premium setting, including the level of loan premium and the “discretion” comes from officers’ subjective experiences. The finding supports the moral hazard hypothesis that banks grants the borrowing enterprises of higher credit risk a higher loan premium, due to the asymmetric information exists in borrowers and lenders. Secondly, in the relationships dimension, the corporate rely in a high borrowing level on private but non-financial holding banks and foreign banks will increase the loan premium as the their dependence getting closer; On the other hand, the loan premium decreases with more closer relationship between firms and public sector banks. Also, if companies have a better relationships with banks (dealing with fewer banks), they receive a lower loan premium. And the discussion of the conditions in loan contracts do not support the signaling hypothesis, banks tend to treat collaterals as a tool to reduce moral hazard risk and reduce the possible loss from defaults. In the investigation of dispersion in loan premium, the empirical results illustrate the main factor of “discretion” caused by officers’ subjective experiences: (1) the larger the bank, with more staffs, the method of loan premium granting may be difficult to consist; (2) the positive relation between bank costs and dispersion explain the additional expense may reflect on “discretion”; (3) The salary structure of public sector banks and lending performance link weakly, the officers have no incentive to reduce loan premium to attract their customers, so the public sector banks grants lower loan premium than private banks..
