Miller came under aggressive and accusatory questioning from Camp and other Republicans, who claimed he misled Congress by failing to reveal the extent of the problem at previous hearings dating back a year.
"When asked the truth and you know the truth and you have a legal responsibility to inform others of the truth but you don't share that truth, what is that called?" Camp asked.
"I always answer questions truthfully, Mr. Camp," Miller replied.
A tense exchange with Rep. Diane Black, a Tennessee Republican, involved Miller's denial that what he called the "listing" of names or phrases that triggered extra scrutiny of exemption requests amounted to political "targeting," the word used in the inspector general's report.
Miller acknowledged that the list of triggering phrases was conservative-based, causing Black to cut him off by declaring: "Then I would say its targeted. You can't have that both ways."
GOP Rep. Devin Nunes of California later asked why Miller resigned if he wasn't personally involved in the improper acts. Miller replied: "I resigned because as the acting commissioner, what happens in the IRS, whether I was personally involved or not, stopped at my desk."
"And so, I should be held accountable for what happens," he said. "Whether I was personally involved or not, a very different question, sir."
Another Republican, Rep. Tom Reed of New York, took exception with Miller's characterization of his resignation, noting it meant he would retire with full benefits and "nothing bad is going to happen to you."
With an incredulous grin, Miller responded: "Nothing bad is happening to me, congressman?"
Reed remained stern-faced, noting Miller continued to get his taxpayer-funded salary.
"You're getting paid for being here today, right?" Reed asked, to which Miller, his smile gone, dryly replied: "Right."
After the hearing, Camp described a "disturbing lack of detail and information" during testimony.
IRS official denies intentional political targeting, lying to Congress - CNN.com