Make Marriage Great Again Act of 2025 This bill modifies the federal income tax rate brackets for married individuals filing joint federal income tax returns so that they are twice the amount of the federal income tax rate brackets for unmarried individuals filing federal income tax returns (thus eliminating the tax effect commonly known as the marriage penalty). Further, the bill eliminates the federal income tax rate brackets for married individuals filing separate federal income tax returns for tax years beginning after December 31, 2024. (An income tax rate bracket is a range of income that is taxed at a specific percentage to determine an individual’s income tax liability.) Thus, under the bill, the federal income tax rate bracket amounts that apply to a married individual are either (1) the individual federal income tax rate bracket amounts if such individual files an individual federal income tax return, or (2) twice such amounts if the individual files a joint federal income tax return with their spouse.