Human error is leading Social Security to overpay or underpay a significant number of beneficiaries with disabilities, an inspector general’s report indicates.

In a review of so-called manual computation practices at the Social Security Administration, federal officials found that mistakes are frequent when staffers manually calculate the benefits a person should receive from Supplemental Security Income, or SSI, a benefits program for those with disabilities.

Manual computations can be triggered when a recipient’s situation changes. For example, if a person moves and their living expenses are altered or if they experience a change in income.

Advertisement - Continue Reading Below

However, a report from the Social Security Administration Office of the Inspector General found major flaws in the manual computation process. As a result, they project that more than 14,000 beneficiaries were overpaid and over 18,000 were underpaid between July 2006 and June 2008. What’s more computations often were not reviewed by a second staffer, as is mandated.

Basic monthly payments for a single SSI recipient are $674 monthly or $1,011 monthly for a couple.