This research is done at PT Mitra Pinasthika Mustika Finance Branch Medan which engaged in field of financing vehicles and heavy equipment. The purpose of this research is to analyze the comparison between gross up method and net basis method for calculating income tax article 21. The observed fiscal year is 2018, and company applies net method to calculate income tax article 21. The analysis is conducted to determine whether net basis method and gross up method in the calculation of income tax article 21 can save corporate income tax payments. The method used by the writer in this research is quantitative method. Based of research result, conclusion of this research is that the implementation tax planning on Article 21 - Income Tax with gross up method has an effect in minimizing corporate's income tax at PT.Mitra Pinasthika Multi Finance Medan. With gross up method, the company can recognize Article 21-Income Tax Allowance as deductible expense with result that corporate income tax can be reduced. Meanwhile in the net method, company cannot recognize Article 21-Income Tax expenses deduction in calculating corporate's income tax. With net method, the Article 21- Income Tax year 2018 amount to Rp 51,082,876 and corporate's income tax expense year 2018 amount to Rp 1,553,753,348 Should company used gross up method, the article 21 income tax and corporate's income tax year 2018 are Rp 58,597,168 and Rp 1,541,205,594. Respectively, the implementation of gross up method on Article 21 Income Tax, will cause the increase of Article 21-Income Tax in the amount of Rp 7,514,292, and the decrease of corporate income tax expense in the amount of Rp 12,547,754. The net impact is a tax saving of Rp 5,033,462 for the company.