BS
IRS already said that is false
Perhaps his returns show donations to Planned Parenthood
Trump said “It’s possible”
IRS gave a general statement about tax returns, then an IRS guy publicly stated he wouldn't recommend releasing forms if he's under an audit.
There is nothing stopping the Cruz or Rubio from releasing their returns either. They are the ones sniveling about releasing returns. Personally, I think it is idiotic for any candidate to do so but professional establishment politicians seem to think it is the thing to do.