電子商務發展對於現行加值稅制與查核技術已造成相當影響，世界各國在課稅技術方面，均難以有效掌握相關交易對象及內容，造成各國面臨稅收大量流失之危機，如何擬訂有效的政策，是目前各國稅務政策的當務之急。然而，針對B2C及C2C對於加值稅稅收之影響，實證研究則相對缺乏。據此，本研究是以台灣自2004年至2014年間時間序列資料，包括B2C及C2C電子商務市場產值與加值型營業稅稅收（以下簡稱加值稅稅收）間之關係，並運用Stata軟體進行敍述性統計、迴歸分析及ADF單根檢定。 本文研究結果顯示，B2C市場產值對加值稅稅收的影響程度顯著，且是正向關係，表示B2C產值愈多，愈有利於加值稅稅收增加；反之，C2C市場產值對加值稅稅收的影響程度則是呈現顯著負相關，表示C2C產值愈多，愈不利於加值稅稅收的課徵，可推論現行課稅技術尚難以掌握課稅主體、課稅客體、交易額、交易類別及交易地點等。在銷售者逃避稅捐而未依規定辦理登記報繳稅捐情況下，猶如地下經濟般確對營業稅稅收有不良影響。是以，本文提出以下建議： 一、明定不得於網路拍賣平台以外從事交易。 二、明定從事網路拍賣須透過第三方支付平台付款。 三、加強金流、物流及資訊流等資料之蒐集。 四、建立網路交易平台及第三方支付平台代收代繳稅款制度。 五、建立政府部門資訊通報交流機制。 六、成立網路交易專責查核小組。 The development of Electronic Commerce(EC) has brought a significant impact on existing Value-Added Tax(VAT) and practices in force. It is difficult for countries around the world to effectively obtain taxation information of transaction parties and contents, which results in tax erosion. It is a globally urgent matter to set up effective regulations and laws. However, there are relatively few empirical studies on influences of B2C and C2C on VAT. Accordingly, this study focuses on time series data from year 2004 to 2014 in Taiwan, including the relationship between B2C and C2C EC markets on output values and VAT collections（abbreviated as value-added tax hereafter）, and runs descriptive statistics、regression analysis and ADF utilizes by Stata software. Research result has shown wide and positive impact of B2C market output values on VAT collections, which means B2C output values are beneficial generating VAT. On the contrary, C2C market output values have negative influences on VAT collections, which means C2C output values are unfavorable generating VAT. We are able to infer that there are difficulties for current taxation practices to control subjects of taxation, objects of taxation, transaction volumes, transaction types and trading locations. Similar to underground economy, tax avoidance and violation of registration of Sellers also impose adverse influences on VAT collection. In conclusion, this study proposes the following suggestions: 1.Stipulate that no transaction allowed outside internet auction platforms. 2.Stipulate that third-party payment should be introduced when engaged in internet auctions. 3.Strengthen data collection on cash flow, logistics and information flow. 4.Establish internet trading platforms and withholding tax systems on the third-party payment platforms. 5.Establish information bulletins and communication mechanisms in public sector. 6.Eestablish internet-transaction-specified examination group.
