Romney tells CNN he's complied with the law by filing a financial disclosure statement.
Romney so far has released one complete tax filing, for 2010, along with an estimate for 2011. He filed for an extension for his 2011 tax return.
Democrats are accusing Romney of being secretive and taking advantage of tax loopholes that aren't available to average Americans. The former Massachusetts governor has also come under attack for accounts he has held in Switzerland, the Cayman Islands and Bermuda.
Romney's fortune is estimated at $250 million. The bulk of it comes from Bain Capital and the return on investments from the company.