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One of the most fundamental problems in Iranian tax system is the lack of reliable estimates for tax revenues. The present research work tries to estimate the tax revenues for Ghazvin province for the next period of 10 years. Time series models and intervention methods are used in the forecast. Since the mid-1386, and due to a number of unknown factors such as the ambiguities in tax law and the delayed tax payments as exogenous variables, the realized tax revenues has diverged from the planned level. The main policy recommendation resulting from this research work is that attempts should be directed towards clarification of taxing system and the related tax rules and regulations.