Former national security adviser John M. Poindexter, convicted of all five felony charges lodged against him for directing a coverup of the Iran-contra affair, will continue to receive his government pension of about $58,000 a year.

But Oliver L. North, Poindexter's onetime subordinate in the White House, has lost his government pension of about $23,000 a year even though he was convicted of fewer charges -- three felonies -- for his role in the biggest scandal in the Reagan presidency. North was acquitted of nine other counts.

The two former career military officers -- Poindexter is a retired Navy rear admiral and North a retired Marine Corps lieutenant colonel -- are treated differently because North was convicted of a charge prohibiting the destruction or altering of government records. The statute he was convicted of violating carries a provision that prompted the Navy to cut off North's retirement pay.

Poindexter was not charged under the same statute.

Many members of Congress -- including liberals such as Rep. Barney Frank (D-Mass.) and Sen. Joseph R. Biden Jr. (D-Del.) -- think the provision causing North to lose his pension is unfair and are trying to change it. They point out that even a retired civilian government employee convicted under the destruction-of-documents statute still would be able to receive a pension.

The key issue for North is the peculiar way military retirement is defined. Retired regular military officers are still considered to be members of the armed forces, and technically are not paid a pension but a smaller salary for their reduced service.

The destruction-of-documents statute under which North was convicted stipulates that anyone who holds an "office" in the government forfeits his job. The General Accounting Office has interpreted that to mean that North, though retired, still holds an office and "there is serious doubt" he can receive a pension.

Legislation in the Senate and House would exempt retired military officers from the provision that has affected North's pension.

The issue of retirement pay is separate from the sentences North and Poindexter received after their Iran-contra convictions.

North was fined $150,000, placed on probation for two years and ordered to perform 1,200 hours of community service work. Poindexter was sentenced to a six-month prison term; he was not fined.

Both are appealing their convictions. Poindexter remains free, pending the outcome.

After North was sentenced last July, his conservative supporters in Congress introduced legislation to restore his pension, and a bill to reinstate it passed the Senate in November, 78 to 17.

Joining Sens. Jesse Helms (R-N.C.) and Strom Thurmond (R-S.C.) were liberal Democrats, including Biden, Sen. Alan Cranston (Calif.) and Majority Leader George J. Mitchell (Maine).

In the House, Frank has joined Reps. Gerald B.H. Solomon (R-N.Y.) and William L. Dickinson (R-Ala.), both conservatives, to push similar legislation.

Frank and Biden have said their support for the legislation grows out their desire for equal treatment of all federal employees, military and civilian, not out of any warmth for North.

"I am not real anxious to help Ollie North in any way at all," Biden said during the Senate debate. "I think Ollie North should be in jail."

But, Biden said, "equity dictates that we change the law."

A Senate Judiciary Committee report on the North pension said former members of Congress convicted of felonies or ethical misconduct can receive their pensions.

Helms pointed out that in the drug bill passed by Congress in 1988, "there was a provision which is now law that allows convicted drug dealers, even those convicted of repeated offenses, to continue to receive 'any retirement . . . or other similar benefit.' "

The law governing pensions for federal employees convicted of felonies has changed considerably over the past 35 years. Under the current statute, a conviction does not automatically result in loss of pension for federal employees.

In 1954, outrage over the fact that former State Department official Alger Hiss could still receive a pension after being convicted of perjury led Congress to bar pensions for any federal employee convicted of a felony related to their work. Hiss was convicted of lying when he denied that he supplied secrets to the Soviets.

The law was modified in 1961 in response to reports that federal employees convicted of minor offenses were losing their pensions. The revisions, which are still in effect, require forfeiture of retirement pay only if a person is convicted of a national security-related crime such as sabotage or espionage.

But, officials said, the modifications in what became known as "the Hiss Act" did not eliminate the provision in the destruction-of-documents statute that led to the cutoff of North's pension.