From a recent report by Social Security's Office of Inspector General (OIG):
... In Fiscal Years (FY) 2015 and 2016, SSA [Social Security Administration] issued approximately 1.1 million claimant representatives’ direct-fee payments totaling approximately $2.6 billion. We identified 39,024 beneficiary claims where SSA may have collected an incorrect user fee. From this, we selected a random sample of 50 beneficiary claims for review. ...
SSA technicians applied an incorrect user fee for 26 (52 percent) of our 50 sampled beneficiary claims. Generally, this occurred because technicians’ authorization of claimant representative fee payments involved manual, complex, and error-prone postings to the electronic records. We estimate d SSA incorrectly applied user fees for 20,292 beneficiary claims, which resulted in SSA over-assessing $338,916 and under- assessing $603,133 to claimant representatives.