His adjusted gross income varied from about $659,000 in 2007 to more than $1.1 million in 2009. In 2010, Santorum earned $923,411.

According to the IRS-1040 forms released by the Santorum campaign, the former Pennsylvania senator paid an effective tax rate of roughly 28.5 percent in 2010.

That is a substantially higher rate than what Mitt Romney paid the same year, according to the former Massachusetts governor’s tax returns, which his campaign released in January.