CNN's Chris Cuomo asked Trump about Mitt Romney demanding the billionaire release his tax returns.

"The one problem I have is I am always audited by the IRS, which I think is very unfair," said Trump. "I don't know — maybe because of religion, maybe because of something else, maybe because I am doing this [running for office], though this is just recently."

Cuomo asked Trump to clarify what he meant, to which Trump responded, "Well, maybe because of the fact I am a strong Christian and I feel strongly about it, and maybe there is a bias."

When Cuomo questioned the legitimacy of Trump's claim, the Republican frontrunner pointed to the long running scandal involving the IRS targeting conservative groups for extra scrutiny based on their names or political themes.

Meanwhile, during the debate itself, Ben Carson also revealed how he had been politically targeted by the IRS after he publicly criticized Barack Obama.

"I never had an audit until I spoke at the National Prayer Breakfast. And then all of the sudden they came in and said, "We just want to look at your real estate dealings." And then they didn't find anything. And then they took a look at the whole year. And they didn't find anything. And then they looked at the next year and they didn't find anything. And they won't find anything… The fact is the IRS is not honest and we have to get rid of them," said Carson.