Marriage Penalty Offset Tax Credit Act of 1980

Marriage Penalty Offset Tax Credit Act of 1980 - Amends the Internal Revenue Code to allow married individuals filing jointly a nonrefundable income tax credit equal to ten percent of the earned income of the spouse who earns 50 percent or less of the combined earned income of both the husband and wife for the taxable year. Limits the amount of such credit to $500 for the taxable year. Requires the reduction of such credit by one percent for each percentage point by which the lower income spouse's earned income is below 30 percent of the couple's combined earned income.