Two former staff at the Electronic Monitoring Service (EMS) are among 29 people charged after an inquiry into the misuse of tags fitted on offenders.
It is alleged the employees took money to fit tags loosely so they could be removed. The tags help ensure curfews and court orders are obeyed.
The police investigation began when an offender was arrested when they should have been under curfew.
The two men are accused of conspiracy to pervert the course of justice.
The investigation, called Operation Glen Falls, was centred on the east London borough of Newham and began in February this year.
The former employees are Martin Crean, of Romford, east London, and Jason Gundry, of Barking, east London, both 46.
The other 27, who are from either east London or Essex, are believed to be offenders who allegedly took advantage of the scam.
All of them will appear at Thames Magistrates' Court next month.