(CNN) - The Republican National Committee announced Tuesday, the day Americans file their taxes, it's suing the Internal Revenue Service over withholding records involved in the agency's targeting of conservative and other groups.
House Oversight Committee Chairman Darrell Issa (R-California) has spent nearly a year investigating why the agency used conservative political terms like "Tea Party" and "patriot" to flag some applications for tax-exempt status.
RNC Chairman Reince Priebus said his group filed suit on Tuesday against the IRS over its legal obligation to fulfill the RNC's request to review documents in the IRS used in its criteria for determining tax-exempt organizations.
"On Tax Day especially Americans deserve to know whether they can trust the agency to which they're sending their taxes," Preibus said. "If the IRS and the Obama administration don't have anything to hide, why not answer the request?"
Priebus said the RNC made the request last May, nearly one year ago, and since then, the IRS has asked for several extensions to fulfill the request but has yet to provide the RNC information, as required under the Freedom of Information Act.
Last year, reports surfaced that conservative groups seeking tax-exempt status were being targeted by the IRS, sparking outrage from Republicans and calls of misconduct by the Obama administration. Disclosures later revealed, however, that the IRS targeted liberals as well as conservatives in assessing applications for tax-exempt status.
The IRS has said it was not targeting groups out of political bias, but because it was trying to determine whether the groups' primary activities were social welfare, rather than political activity.
The RNC's announcement comes after the Republican-led House Oversight Committee voted 21-12 last week to charge former IRS official Lois Lerner with contempt of Congress for refusing to answer questions about the agency's targeting.
CNN's Dana Davidsen and Lisa Desjardins contributed to this report.