It has cost the Department of Correctional Services R9.8bn to keep prisoners behind bars as well as monitor those on parole in the past five months, a committee in Parliament was told on Wednesday.
This is 47.9% of the department's budget of R20.6bn, and leaves R10.7bn for the rest of the 2014/15 financial year.
Incarceration alone cost R6.5bn, with R335m underspent due to 2 066 vacancies in the department.
At least R63m was overspent because the department had to get a contract for a “nutritional service” because the Department of Public Works could not fix dysfunctional boilers.
The department also spent R75m on fleet services - higher than the original plan of R45m - because of the high number of vehicle repairs needed on the department's ageing fleet.
According to its annual report for 2014/15 the department had 243 correctional facilities.