Rep. John Carter (R-Texas) acknowledged Monday that he had failed to report $48,000 in capital gains from stock sales in 2008, in addition to the approximately $300,000 he previously acknowledged misreporting in 2006 and 2007.

After Roll Call inquired about his annual financial disclosure forms, which appeared to indicate large sales of Exxon stock but no profits, Carter took to the floor Wednesday to acknowledge that he had failed to report about $300,00 in profits from those sales in 2006 and 2007. He filed amended disclosure forms and posted his income tax returns from those years on his Web site to prove that he had paid taxes on the gains.

Carter, who has led the Republican charge to strip Ways and Means Chairman Charlie Rangel (D-N.Y.) of his gavel pending an ethics committee investigation of Rangel’s financial disclosures, tax issues and other concerns, challenged Rangel and Treasury Secretary Timothy Geithner to release their tax returns to clear up questions about their taxes.

On Thursday, Carter’s office told Roll Call that during a final review of the Congressman’s disclosure forms, Carter had discovered that he had also failed to report capital gains on Exxon stock sales for 2008.

Carter earned just over $48,000 in a 2008 transaction that was described on his original disclosures as involving $50,000 to $100,000 worth of Exxon stock.

Carter’s office said the Congressman is making his 2008 tax forms public as well, again to show that he properly paid taxes on the sales and simply failed to record them properly on his Congressional disclosure forms.

Rangel’s office did not respond to Roll Call’s request that he release his tax returns.