(CNN) – Republican Sen. Scott Brown's income more than doubled when he entered the Senate due in large part to a book advance he received after winning the Massachusetts special election, according to tax returns released Friday by his campaign.
Brown reported earning more than $294,000 in 2009, before he entered the Senate and $840,000 in 2010, his first year in the upper chamber of Congress. In the most recent tax year Brown and his wife, television reporter Gail Huff, reported bringing in $510,856.
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The Browns paid $123,642 in taxes in 2011, or an effective tax rate of 24.2% and contributed $16,487, or 3.2% of their total income to charity.
The first term senator, who won a special election after Democratic Sen. Ted Kennedy passed away in 2009, has received a congressional salary of $174,000 per year. His income was aided by a $700,000 advance of his memoir "Against All Odds" that was released in 2011.
The release of Brown's tax returns is the latest seemingly political ploy in the bitter Senate election between the former Massachusetts state senator and challenger, Democrat Elizabeth Warren.
On Tuesday Brown called on consumer protection advocate Warren to release six years of tax returns, a step he said he would take. Warren responded saying she would release four years of returns.
Team Brown criticized the four year decision, questioning what the Harvard professor is "hiding."
"What is in her tax returns during these years that Warren is so afraid voters might learn?" Brown Campaign Manager Jim Barnett said in a statement Friday.
But a spokeswoman for Warren said she intended to release four years of returns, which covers her "entire time in public service."
"She is providing the people of Massachusetts with a transparent and full accounting of her financial situation," spokeswoman Althea Harney said in a statement to CNN earlier in the week.
The Warren campaign did not immediately return a request for comment on Friday about a timeline for the release.
Talk of tax returns came after The Boston Globe requested both candidates release the last five years of figures earlier in the year.
Now both sides are playing politics with issue, attempting to use the returns to help craft a negative image of their opponent and contribute to their personal narratives.
Brown has pointed to Warren's personal wealth while trying to protect his image as an everyman. He memorably traveled around the state in 2009 and 2010 in his pick-up truck talking to voters. Warren is marketing herself as a champion of the middle class, pushing back against GOP criticism that her wealth makes her an unsuitable voice for the average Massachusetts voter.
- CNN's Ashley Killough contributed to this report.