Fiscal reconciliation is an adjustment of commercial financial statements that have been prepared by the taxpayer with the provisions of the tax legislation. In the reconciliation, there emerged differences between commercial profit and taxable income in the form of fiscal correction, which can be categorized into two groups: permanent differences and temporary differences. This study aims to determine the effect of permanent differences and temporary differences on corporate income tax either partially or simultaneously. The research was conducted in 6 Telecommunications Industry Company listed in Indonesia Stock Exchange, with a financial statements sampling period of 2009 until 2011. The research methodology used in this study is a descriptive analysis method, with a survey-study approach. Statistical testing using multiple linear regression analysis. The results showed, partially permanent differences have significant influence on corporate income tax, but temporary differences do not have significant influence on corporate income tax and simultaneously, permanent differences and temporary differences are altogether have significant effect on corporate income tax.