Convicted criminals in England and Wales will have to pay up to £1,200 towards the cost of their court case under new rules, it has been revealed.
Justice Secretary Chris Grayling said the Criminal Courts Charge would ensure criminals "pay their way".
The fees, which come into force on 13 April, are not means-tested and will start at £150.
The Magistrates' Association warned the new charge could place a burden on people with little income.
It also warned that innocent people could be encouraged to plead guilty to avoid the risk of higher payments, as those who admit their offences will pay less than those convicted after a trial.
The government said the new charge would be reviewed three years after implementation, but the Magistrates' Association said it should be reviewed after six months.
The fee will be paid on top of fines, compensation orders and defendants' own legal charges.
It will not be linked to the sentence given, but will be set according to its type of case, with the minimum charge for magistrates' courts and the maximum level for crown court cases.
A government assessment suggested that by 2020 the system could raise £135m annually after costs, but it warned that by then the court service would be owed £1bn in unpaid fees.
Courts already have the power to award "costs" against criminals as part of their punishment, but that is to reimburse any expenditure by the prosecution team that the court decides it would be "just and reasonable" to have paid by a losing defendant.
The new charge will mean offenders make a direct contribution to the costs of running the court itself.
Under the current rules, convicted criminals can also be ordered to make payments to cover compensation for victims, as well as a Victim Surcharge - which funds victims' services.
All of this is separate from the sentence itself, which in some cases can be a fine.
'Not able to pay'
Mr Grayling said: "We're on the side of people who work hard and want to get on, and that is why these reforms will make sure that those who commit crime pay their way and contribute towards the cost of their court cases."
Richard Monkhouse, Magistrates' Association chairman, told BBC Radio 5 live: "We see an awful lot of people who are offending because they have no money, so just slapping another fine on them, another costs element on them, isn't actually going to make a big difference if they're not able to pay."
Justin Rivett, a solicitor with Warren's Law and Advocacy, said the charges could result in innocent people pleading guilty in order to pay lower charges than if a court found them guilty.