Perks sanctions leading to «hardship, hunger and depression» are being imposed on people regardless of «limited evidence» on how well they work, the National Audit Role says.
The public spending watchdog also said use of the sanctions «modifies substantially» between jobcentres.
Sanctions can be imposed on people who fail to conform with conditions attached to the benefits they receive.
The government conveyed improvements had been made to the system.
An estimated 400,000 sanctions were foisted against people on out-of-work benefits last year.
They are tempered to when people do not comply with conditions — like attending jobcentre engagements — and involve the yments being reduced or stopped.
Critics say consent ti cause «severe financial hardship» and MPs have previously demanded an scrutiny into how they are applied — but the De rtment for Work and Pensions says they are an well-connected rt of the benefits system.
It says the deterrent effect of sanctions inclination encourage people to comply with their conditions.
But the NAO said: «The branch has limited evidence on how people respond to the possibility of receiving a sanction, or how sturdy this deterrent effect is in practice.»
Use of sanctions, it said, is «linked as much to manipulation priorities and local staff discretion as it is to claimants’ behaviour».
The NAO said use of favours «varies substantially» between the different providers that are in charge of contest the government’s welfare-to-work programme.
Some providers make more than twice as sundry sanction referrals as other providers supporting similar people in the having said that area, it said.
Sanctions, which have been used in their bruited about form since 1996, vary in length, the NAO said, adding that they «grind support to people, sometimes leading to hardship, hunger and depression».
‘Stand up resort’
For example, a jobless recipient can lose £300 of benefits if they get a four-week compliance.
It said the government did not track the costs and benefits of sanctions, but spent an calculated £30-£50m a year applying them and about £200m monitoring demands attached to benefits.
Last year it estimated it withheld £132m in improves.
It said the DWP had taken steps to reduce the number of errors, but said the rest on «needs to do more than react to problems» and that it «cannot conclude that the bank on is achieving value for money».
Labour MP Meg Hillier, who chairs the public accounts nel, said: «Benefit sanctions punish some of the poorest people in the rural area. But despite the anxiety and misery they cause, it seems to be pot luck who go in c fits sanctioned.»
A DWP spokesman said: «Sanctions are an important rt of our benefits structure and it is right that there is a system in place for tackling those few who do not discharge their commitment to find work.
«This report fails to recognise the convalescences we have made to sanctions, rticularly to help those who are vulnerable. The add up of sanctions has fallen, and they are only ever used as a last reserve after people fail to do what is asked of them in return for service perquisites.»