Self assessment system used in Indonesia to provide more flexibility for taxpayers to calculate, pay, and report its own taxation liabilities. It is pointed out will encourage taxpayers to make tax, It is allegedly going to encourage taxpayers to make tax planning, so that the tax on companies will be relatively small. This study tried to assess the effect of the Good Corporate Governance implementation on Tax Planning with affected Accounting Conservatism as an intervening variable. Thus this study will to know whether the implementation of good corporate governance can leads to an increase of taxpayer compliance and will be able to suppress the behavior of taxpayers in tax planning. Addition this study presents accounting conservatism, whereby if the taxpayer (company) to implement good corporate governance properly then Hopes accounting conservatism will reduce behaviors that ultimately reduces behavioral planning done taxpayer. This study used 114 company on the Indonesia Stock Exchange. Further descriptive statistical approach is used to describe each study variable, while the hypothesis was tested by Path analysis approach. The results showed that the Principle of Transparency direct effect on Tax Planning. Principles of Transparency and Fairness directly influence the behavior of Accounting Conservatism. Principles of Accountability, responsibility, independency, and fairness has indirect effect on Corporate Tax Planning and Accounting Conservatism on the other side. Whereas the Accounting Conservatism Behavior influence Corporate Tax Planning.
Keywords: Good Corporate Governance, Conservatism, Tax Planning