The proposed new Senate code of official conduct, being draftd by a special committee, will bar members and top staffers from also working for pay as lawyers, insurance or real estate agents, physicians, architects and other "professional services."

The curb on professional income began originally as a flat prohibition against members and staffers who are lawyers earning $25,000 or more from practicing in addition to their Senate business. It was subsequently expanded to include other professions and goes beyond any provision in the House ethics package.

The complete Senate ethics package has been subjected to some tinkering over the past few days to bring it into closer line with the House ethics code approved last week.

The draft code, which had been tentatively agreed to by the committee earlier, is expected to be made public Friday and debated on the floor, possibly as early as Tuesday.

Like the House code, the Senate draft code provides a limit of 15 per cent of a member's salary to any additional earned income, such as honoraria, he will be permitted to receive. Also in line with the House, the Senate draft permits unlimited unearned income to be received by a member from investments.

As does the House code, the senate proposal calls for extensive public disclosure of all income, investment holdings and gifts.

The Senate drafters, however, put into their package a series of rules not contained in the House code:

Former senators are barred for one year from lobbying their former colleagues or Senate staffers on behalf of a client. The same one-year lobbying prohibition applies to committee staffers and Senate aides.

The income disclosure provisions, applicable to senators, are made enforceable on individuals who announce themselves as candidates for a Senate seat. Under the code, such an individual would have to make public his income for the prior year at the time he announces for the Senate.

The outside income limitation of 15 per cent is applied to Senate staffers earning $35,000 per year or more. Such an individual is permitted to accept speaking honoraria of up to $300 per speech and a total of $1,500 per year.

Senators are permitted honoraria of up to $1,000 per speech - though the total is subject to the yearly earned outside income limitation of about $8,600, or 15 per cent of a senator's annual salary of $5,500. Senators are allowed to receive honoraria up to $25,000 in one year if they contribute the excess above $8,600 to charitable organizations and "no tax benefits accrue" to them.

Committee employees earning $25,000 a year or more would be required to divest themselves of "holdings which may be directly affected by the actions of the committee for which the works . . ." That provision could be waived with the written permission of the senator for whom the employee works and the Senate ethics committee.

There is no similar provision in the code requiring senators to divest themselves of holdings that could involve potential conflicts of interest.

Senators and top staffers are barred from serving on the board of directors or as officers of publicly held of publicly regulated corporations.

Senators are prohibited from converting excess campaign contributions to their own personal use, even after they have been defeated or retired from Congress. At present, as long as a retiring member of Congress pays taxes on excess campaign funds, he can use them for personal purposes.

The Special Committee on Official Conduct, whose chairman is Sen. Gaylord Nelson (D-Wis.), has still not decided what to do about three items:

A proposal to force off the Senate payroll employees who are "engaged substantially in campaign activities"; a provision setting up the ethics committee as the body to handle an equal employment opportunities code; and a tough procedure for enforcement of the entire code.

All three proposals were put forward by Sen. Dick Clark (D-Iowa), a member of the special committee.