Suzy Khimm of the Washington Post's Wonk Blog:

Rick Santorum’s socially conservative brand has helped him break through with a last-minute surge in Iowa. But his agenda isn’t restricted to reimposing “Don’t Ask, Don’t Tell,”outlawing gay marriage nationwide, or promoting prayer in public schools. Santorum also wants to use the federal tax incentives to promote traditional marriage and families.

“Tax policy as social policy” is the most distinguishing characteristic of Santorum’s tax reform platform. The Pennsylvania Republican wants to reduce taxes by tripling the child tax credit, which currently stands at $1,000 per child. Santorum also wants to reduce federal taxes that penalize married couples. Under the current tax code, some spouses who earn about the same salary on the middle-to-upper end of the spectrum pay more in taxes by filing jointly as a married couple than they would as individuals. Justin Wolfers explains further: “The U.S. has a household-based taxation system which subsidizes married families when one person stays home and taxes most people extra if they choose to marry and both work full-time. The average tax cost of marriage for a dual-income couple is $1,500 annually.”