Victims of violent crime who suffer minor injuries would not be getting any compensation after changes being effected in England, Wales and Scotland.
Injuries such as broken nose, mild concussion, temporary deafness or minor burns suffered due to violent crime will not be eligible for compensation.
Shopworkers union Usdaw said many retail staff who get injured in armed robberies and assaults would lose out due to the changes that are being planned.
Ministers have said that the reforms would save £50m off the annual £449m bill.
BBC home affairs correspondent Danny Shaw said the reforms to the Criminal Injuries Compensation Scheme, including the scrapping of five payment levels, were the most significant since a sliding scale of payments was introduced to simplify it 16 years ago.
Usdaw criticised the MPs who voted for changes saying that the MPs would never be able to say that they put victim’s interest first.
In September, in a move hailed by Victim Support as "a turnaround", Justice Minister Helen Grant said she would reconsider the plans after the charity's protests as well as those by MPs and unions.
But when a parliamentary committee met at the start of this month, the unchanged plans were approved by nine votes to seven.
That led Labour to accuse the government of "stacking" the Seventh Delegated Legislation Committee by ensuring people on the government payroll, including four parliamentary private secretaries, turned up to vote.
The Ministry of Justice said that it was dedicated to preserving compensation to the most seriously-injured victims of crime.
For people who suffered less serious injuries the taxpayers money would be better spent for providing support and help rather that what were often small payments which came about well after the crime had been committed a spokesperson said.