推計課稅，係指當稽徵機關無直接證據，且已盡調查之能事，得採推估方法，對納稅義務人核課稅捐。稅務證據在稽徵行政程序及司法爭訟程序，占有舉足輕重之地位，採推計課稅影響所及舉證責任、證據評價、證明程度等爭議問題，為本文介紹之重點。
因推計課稅係採間接證明法，原則上應容許當事人舉證推翻稽徵機關所作成之課稅處分，本文整理實務判決，將推計課稅之處分原因類型分門別類，並用一套判斷流程，在稽徵機關作成課稅處分之際，先視納稅義務人有無履行協力義務，而協力義務之界限究竟為何，來分析推計課稅制度於實務上運用之實際結果為何。
最後於文末提出淺見，文中所提出之問題，將會於各章節分述探討，而法院應本於公平、公正不失偏頗之立場謀求徵納間之平衡。
Presumption of fact means that a tax authority has no direct evidence, and exhausted administrative investigation, could have used a presumption method of taxable fact to impose tax on taxpayer. Evidence of taxation play an important role under Administrative and judicial process. Issues related to presumption of fact as burden of proof, character of evidence and possibility of proof are being discussed in this thesis.
Because presumption of fact is an indirect proof method, a taxpayer is able to rebut the presumption to overthrow a taxation by the authority. This article collects judicial decisions, to classify the cause of presumption of fact by using judgment of the process in a taxation under which a taxpayer is obligated to cooperate with the tax authority and the its limits in order to analysis the court view under presumption of fact in a tax conroversy.
The conclusion of the issues discussed in this thesis is that a judge have to decide equally and impartially, in order to strike a balance between taxpayer and tax authority.
