This dissertation quantifies the magnitude of the marriage penalty tax and measures its distributional effects on the general population. Estimates of the marriage penalty tax were calculated based on the effects of the most recent tax act on all taxpayers according to class of income. The study measures the distribution of the marriage penalty tax using income tax data for the year 2000 and projects changes that result from the Jobs and Growth Tax Relief Reconciliation Act of 2003. Data for analysis was obtained from the Internal Revenue Service’s Statistics of Income (SOI) database and the Census Bureau’s year 2000 Current Population Survey (CPS) database. On signing the new tax act, President Bush said that the current tax code frequently taxes couples more after they get married and that the marriage tax contradicts American values and any reasonable sense of fairness. However, even after passage of the new tax act, results of the study indicate that while the marriage penalty tax is reduced, it continues to negatively affect the American family.