WASHINGTON (AP) — Republican presidential front-runner Donald Trump is sticking to his new explanation for why he can't release copies of his recent tax returns just yet: The Internal Revenue Service is auditing him, as he says it has for 12 consecutive years.

Tax experts say that explanation has them scratching their heads because an audit would not prohibit the documents' release. Trump's rationale is also emboldening critics who say Trump's personal finances remain unexamined. The normal statute of limitations for IRS audits is three years, making notable Trump's statement that four or five years of filings are currently under review.

Trump has insinuated that he has been singled out for audits. But tax experts say it is normal for the IRS to disproportionately focus on high earners with complex returns.