Forty-one percent per a Treasury Inspector General for Tax Administration report. Luckily, the TIGTA has suggestions:
TIGTA recommended that the IRS analyze the accuracy of returns prepared at individual volunteer sites to identify patterns and concerns on which to focus education, training and accountability. The report also suggested that the IRS improve the intake sheet that is used at the start of the tax prep process to include questions based on new tax laws and filing status, and improve the reviews of intake sheets and returns completed at volunteer sites.
The TIGTA anonymously sent auditors to volunteer testing sites which seems pretty unfair. If those sneaky bastards had reviewed the tax returns instead of Monday morning quarterbacking the volunteers maybe there would’ve been less mistakes. Just a thought.