But Sparks reported giving little to charity - just $65 - while Bentley donated more than 10 percent of his taxable income and wrote off six-figure losses that reduced what he had to pay to the federal government.
The 2010 governor's race is unusual because both nominees for governor have released their tax returns. In most elections, neither candidate does.
The tax returns offer a glimpse into the candidates' lives outside the political arena.
Sparks, who is no longer married, filed as a a single taxpayer who relies mostly on his salary as state agriculture commissioner.
Bentley filed a joint return with his wife, Martha, who's listed as a homemaker. The tax return presents Bentley as a a successful dermatologist in Tuscaloosa with a six-figure income who could afford to underwrite his Republican primary campaign with $1.9 million in personal loans.
Bentley unveiled his 2009 return in May and cited it as an example of the openness and ethics he wants to bring to state government.
Sparks released his tax return at the end of his debate with Bentley on Thursday night in Tuscaloosa. He pointed out the significant differences in taxes they paid last year and said Bentley had served in the Legislature for 7 years without "introducing one piece of legislation on ethics."
Sparks reported $74,139 in taxable income on his federal income tax return for 2009, including $73,366 from his salary. He paid $11,981 in federal income taxes.
Bentley, who retired from his medical practice in May 2009 so he could run for governor, had $340,698 in income, but some of that was from a pension and Social Security that was not taxable. He also reported $120,380 in losses from real estate and his farm that reduced his total taxable income to $112,943. He paid $4,884 in federal income tax.
Some of the losses Bentley was able to write off on his federal tax return are not used by the state. His taxable income on his state return jumped to $206,940.
That meant Bentley paid $7,500 in state income tax, compared to Sparks' $2,463.
Another big difference between the two candidates was the charitable contributions they reported. Bentley listed $15,159, while Sparks put down $65.
Bentley's spokeswoman, Rebekah Mason, said he tithes to his church, First Baptist Church in Tuscaloosa, and that made up much of his charitable giving.
Voters will elect Alabama's next governor on Nov. 2.