In the past three years, federal judges have cracked down on white-collar criminals and drug traffickers, often imposing large fines to keep them from profiting from their crimes.

But neither the judges nor the federal courts have paid much attention to whether the fines are ever paid. As a result, the government collects only 55 cents of every dollar that federal judges levy, and many criminals literally are never forced to pay their debts to society, a Senate Governmental Affairs subcommittee has found.

According to the most recent statistics, 22,532 criminal fines, worth $185.6 million, haven't been paid, said Sen. Charles H. Percy (R-Ill.), chairman of the subcommittee on energy, nuclear proliferation and government processes. Nearly all of the fines are owed by white-collar criminals who could pay, but simply don't, he said.

For example:

* A businessman convicted of income tax evasion in 1981 hasn't paid a penny of a $10,000 fine even though federal agents testified that he owned more than a half-million dollars worth of real estate and $35,000 worth of stocks, and had $80,000 in cash.

* A doctor who owns five homes has paid only $2,500 of a $10,000 criminal fine that was imposed in 1978 after he was convicted of stealing $90,000 by filing false Medicare claims.

* G. Gordon Liddy didn't pay his $40,000 criminal fine until 10 years after his conviction for his role in the 1972 Watergate break-in. If Liddy's success as an author and on the lecture circuit hadn't attracted the Justice Department's attention after his release from prison, the government probably wouldn't have taken him to court and forced him to pay his fine, Bill Strauss, the subcommittee's director, said in an interview.

At a recent subcommittee hearing, James I.K. Knapp, a deputy assistant attorney general for Justice's Criminal Division, said collection efforts traditionally have been a low priority.

Usually, he said, "they were assigned to the most inexperienced attorneys or even support staff." The government has to fall in line behind other creditors and rely on the same time-consuming techniques it uses to collect other debts. Many criminals also use sophisticated methods to hide their assets.

A doctor convicted of swindling Medicare of $1.5 million was sentenced to seven years in prison and a $300,000 fine, but he and his wife refused to testify about their assets. The government spent more than a year tracing their finances from New York to the Bahamas and eventually to the Grand Cayman Islands before it was able to force the doctor to pay $50,000 of his fine and arrange a plan to pay the remainder within three years.

In another case, a Miami drug dealer avoided paying a $100,000 fine by divorcing his wife three weeks before his trial and deeding all of his property to her.

But Strauss contends that the biggest problem is still a lack of interest. "Everyone points the other way," he said. Federal judges say it's up to the courts to collect fines, but the courts say it's the U.S. attorneys' job. The attorneys claim the Bureau of Prisons has to do more and the bureau points its finger at the U.S. Parole Commission.

Federal officials also used to claim most of the unpaid fines were old and difficult to collect because the criminals were poor or in jail, Strauss said. But when the department reviewed 4,220 cases recently at Percy's request, it discovered that 75 percent of the fines were less than 13 years old and only 6 percent were owed by prisoners or persons who were considered indigent. In 90 percent of the cases it found that no one had made any attempt to collect the fines.

Percy called the survey findings "outrageous--especially when you consider that five out of every six fines are levied on criminals who do not go to prison."

When a collection effort was made, the survey found it was often inadequate. In one case, a probation officer set up a $10-a-month installment plan so that a convicted felon could repay his $35,000 fine after he was released from prison. At that rate, Strauss noted, it will take him nearly three centuries to repay his fine.

Judges can find criminals in contempt of court if they don't pay their fines, but only one of the cases surveyed was resolved that way.

"We often sensed a reluctance on the part of judges, prosecutors, probation officers and others to collect and enforce fines for fear of imposing hardship on the criminal and family," Strauss said. "But no one questions that when someone is sent to prison that will be a hardship."

If the situation doesn't improve, Percy and Sen. Alfonse M. D'Amato (R-N.Y.) said, they will introduce legislation to make non-payment of fines a criminal offense.

Meanwhile, the Justice Department recently told Percy it will ask U.S. attorneys to do a better job of collecting the fines. It also has proposed legislation that would require courts to consider the financial resources of a defendant before it imposes a fine, set a schedule for repayment, and charge interest or other penalties if a criminal can pay his fine but simply doesn't.

"If we don't let criminals walk away from prison simply because it is inconvenient for them to be there, then neither should we make it easy for criminals to walk away from these fines," Percy said.