From a recent report by Social Security's Office of Inspector General (footnotes omitted):
CPR [Cross Program Recovery] is the process of collecting overpayments for one SSA-administered program by withholding the individual’s payable benefits from another SSA-administered program [recovering an SSI overpayment from regular Social Security benefits or vice versa]. ... The Agency can use CPR to withhold up to 10 percent of individuals’ OASDI [Old Age Survivors and Disability Insurance] monthly payments and either 100 percent of individuals’ SSI monthly payments or an amount that is 10 percent of their income, whichever is lower. ...
The Agency did not always use mandatory CPR to recover OASDI and SSI overpayments, as authorized under SSPA. ....
The Agency could have used mandatory CPR to collect $257,914 in OASDI overpayments from the SSI payments of 49 of the 50 individuals we reviewed. Based on our sample results, we estimate the Agency could have imposed mandatory CPR to collect about $52.9 million in OASDI overpayments from the SSI payments of the remaining 11,268 individuals we identified. ...
The Agency could have used mandatory CPR to collect $248,166 in SSI overpayments from the OASDI benefits of the 50 individuals we reviewed. Based on our sample results, we estimate the Agency could have imposed mandatory CPR to collect about $33.5 million in additional SSI overpayments from the OASDI benefits of the remaining 9,364 individuals we identified.