I noticed that in Paul Ryan's Path to Prosperity he states:
Today, taxpayers spend $168 billion and 6.1 billion hours per year trying to file their tax returns.
The footnote points to this:
National Taxpayer Advocate, 2013 Annual Report to Congress, Internal Revenue Service, 31 Dec. 2013.
That report, in turn, also makes the same claim but the footnote for that references this:
See email from Director, TAS Technical Analysis & Guidance (Dec. 19, 2013).
Which I can't find anywhere. How are you supposed to check these things?