WASHINGTON — Acting Internal Revenue Service Commissioner Steven T. Miller repeatedly failed to tell Congress that tea party groups were being inappropriately targeted, even after he had been briefed on the matter.

The IRS said Monday that Miller was first informed on May, 3, 2012, that applications for tax-exempt status by tea party groups were inappropriately singled out for extra, sometimes burdensome scrutiny.

At least twice after the briefing, Miller wrote letters to members of Congress to explain the process of reviewing applications for tax-exempt status without revealing that tea party groups had been targeted. On July 25, 2012, Miller testified before the House Ways and Means oversight subcommittee but again was not forthcoming on the issue — despite being asked about it.

At the hearing, Rep. Kenny Marchant, R-Texas, told Miller that some politically active tax-exempt groups in his district had complained about being harassed. Marchant did not explicitly ask if tea party groups were being targeted. But he did ask how applications were handled.

Miller responded, “We did group those organizations together to ensure consistency, to ensure quality. We continue to work those cases,” states a transcript on the committee’s website.

He added, “It is my hope that some of the noise that we heard earlier this year has abated as we continue to work through these cases.”

Earlier, Rep. Charles Boustany, R-La., had raised concerns with the IRS about complaints that tea party groups were being harassed. Boustany specifically mentioned tea party groups in his inquiry.

But in a June 15, 2012, letter to Boustany, Miller gave a generic response. He said that when the IRS saw an increase in applications from groups that were involved in political activity, the agency “took steps to coordinate the handling of the case to ensure consistency.”

He added that agents worked with tax law experts “to develop approaches and materials that could be helpful to the agents working the cases.”

Miller did not mention that in 2011, those materials included a list of words to watch for, such as “tea party” and “patriot.” He also didn’t disclose that in January 2012, the criteria for additional screening was updated to include references to the Constitution or the Bill of Rights.

“They repeatedly failed to disclose and be truthful about what they were doing,” said Rep. Dave Camp, R-Mich., chairman of the House Ways and Means Committee, which is holding a hearing on the issue Friday and Miller is scheduled to testify.