"Nothing prevents individuals from sharing their own tax information. The IRS stresses that audits of tax returns are based on the information contained on the taxpayer's return and the underlying tax law—nothing else. The audit process is handled by career, nonpartisan civil servants, and we have processes in place to safeguard the exam process."—The IRS, in [video may autoplay at link] a statement to ABC News.
This is the IRS saying plainly that Donald Trump has no legal reason not to release his tax returns because of an audit.
In other words, this is the IRS very politely calling the president a damn liar.