Most Americans could give you an earful about what’s wrong with the Internal Revenue Service. But could they produce a critique so vast and deep that the executive summary alone is 106 pages?

That feat is performed annually by Nina Olson and her team at the Taxpayer Advocate’s office, an independent body within the IRS. Every year, it must produce a report for Congress that includes 20 or more of the most serious problems taxpayers face when dealing with the agency. This year, the usual two-volume report grew to three, with the addition of “literature reviews” in areas ranging from taxpayer service in other countries to behavioral science lessons for taxpayer compliance.

At the top of the list of IRS shortcomings this year: The agency doesn’t make enough use of behavioral research insights to encourage voluntary compliance with the tax code. (Right, not your top complaint.) Other “needs improvement” areas include taxpayer service (there ya go), the IRS’ debt collection program, and the way the agency evaluates the living expenses of taxpayers on the installment program.

The report gives the IRS credit for better detection of fraud and identity theft but says a lack of flexibility in the IRS’s fraud detection system leads to high false positives in flagging tax returns. That delays refunds.

“IRS filers and business rules used for detecting fraudulent returns and identity theft had many FPRs [false positive returns] over 50 percent” for calendar year 2016, as of September, the report said.

 Along with flagging problems, the Taxpayer Advocate must propose solutions. The top recommendation: Simplify the four-million-word tax code.