Lawyers say the bill to compensate victims of Plymouth paedophile William Goad could run into millions of pounds.
Some of Goad's victims were as young as eight years old
But the money could have to be found from taxpayers, while his personal wealth remains untouched, criminal injury lawyers are warning.
Goad, 60, was jailed for life last year for a string of sexual offences against boys stretching over decades.
The millionaire businessman was described in court as Britain's most prolific paedophile.
Lawyers say if all his victims received £5,000 from the Criminal Injuries Compensation Scheme, the bill could top £17.5m, but a legal loophole means Goad may not be liable to foot the bill.
At the moment, victims have six years to claim from their abuser from when they turn 18, but the time limit for an action lapsed before Goad was convicted.
The Association of Child Abuse Lawyers want that period extended saying many do not know they can claim compensation until it is too late.
Once the period has expired, they can only turn to the government funded Criminal Injuries Compensation Scheme.
Goad, who ran shops and market stalls, was sentenced last October for 14 specimen counts of serious sex offences and two counts of indecent assault.