Two Virginia General Assembly members who either missed all or a major portion of the recent 52-day legislative session collected a tax-free $44 a-day expense allowance for the entire session because of a little-noticed provision of state law.

Both men, and several others who became ill briefly or missed portions of the session for other reasons, were paid under terms of a state law that legislative clerks said today "mandates" the payments whether or not the legislators are in Richmond.

Under that ruling, Sen. Paul W. Manns (D-Caroline), who was critically ill and never made it to Richmond during the session, drew a maximum $2,288 expense payment, in addition to his regular legislative salary of $5,470 a year.

Del. Robert E. Harris (R-Fairfax), who missed the legislature's final 24 days after undergoing surgery for a broken leg, collected $1,056 in expense money for days he was absent from Richmond.

"It's no big deal," Harris, an executive with Rockwell International in Washington, said yesterday. "If it's a big deal, I'll sit down and write a check (to return the money to the state). It's not a big deal with me."

Manns, who spent most of the session recovering from a heart condition in a Norfolk hospital, was reported resting at his home in Bowling Green, near Fredericksburgh, and could not be reached for comment.

However, Senate Majority Leader Adelard L. Brault (D-Fairfax) said the payments to the men illustrated a problem that the drafters of the expense law did not envision. He said he would ask a legislative committee to look into the payments as well as the practice of giving the allowance to Richmond-area legislators who live at home during the session.

House Majority Leader James M. Thomson (D-Alexandria) agreed that the current policy of paying the legislator's daily expenses on weekends, when many lawmakers return home, as well as working days, was "crazy." He said he long had urged a revamping of the policy.

"It never has made any sense, but it has always been that way," he said.

Neither Thomson nor Brault would say whether Manns or Harris should return the expense money they received for days they were not in Richmond. Brault said he would not accept the expense money if he missed an entire session and Thomson said it was "a matter of conscience" as to whether a legislator chose to keep the money.

Neither the House nor the Senate keeps daily attendance records on its members and the per diem expense allowance is paid automatically unless a legislator askes that it be stopped or reduced.

Dels. J. William O'Brien (D-Chesapeake) and Richard S. (Major) Reynolds III (D-Richmond), who left Richmond to attend President Carter's inauguration, each forfeited one $44 expense payment, according to House records. But their cases were the exceptions, legislative aides said.

Senate Clerk Jay Shropshire said he "never" has had a member of the Senate return an expense check.

If either Manns or Harris had been salesmen, the expense money they received while not on the job would have to be listed as taxable income, according to Internal Revenue Service spokesman Larry Batdorf. Under IRS rulings, state legislators are treated like congressmen and thus are allowed to claim the expense allowance for each day their legislature is in session, whether or not they attend the meetings, he said.

Batdorf acknowledged the position may appear "inconsistent," but added, "We are bound to administer the law literally."