Mitt Romney's campaign announced at 5:16 p.m. Friday that the presumptive GOP nominee has filed an extension for his 2011 tax return.

"Sometime in the next six months, and prior to the election, Gov. Romney will file and release the 2011 return when there is sufficient information to provide an accurate return," wrote Romney spokeswoman Andrea Saul in an email to reporters. Six months from now would be Oct. 13, weeks before the election.

The Romneys estimate a total tax liability of $3,226,623 for 2011, according to Saul. They made payments of $3,434,411 in 2011. They made an estimated payment of $887,000 for 2012.

The Obamas and the Bidens released their 2011 tax returns earlier Friday.

Romney released his 2010 tax return in January after being criticized. The returns showed income of $21.7 million in 2010 and an effective tax rate of 13.9 percent, far lower than middle-class earners. The Romneys paid the lower rate because their income was entirely from investments, as opposed to wages. The Romneys have a net worth $190 million to $250 million.

The deadline to file the 2011 federal tax return is April 17.