A state commission has recommended a four-year graduated pay raise for Maryland General Assembly members that would boost a lawmaker's salary from the present level of $12,500 a year to $16,000 in 1979, and to $18,500 in 1982.

The proposal by the General Assembly Compensation Commission automatically becomes law unless it is rejected by legislators at their coming session. Lawmakers can cut the recommended amount but cannot increase it.

For most legislators in Maryland, the job is full-time only during the annual 90-day session.

The nine-member commission also approved a $15-a-day increase in expense accounts for the state lawmakers, giving them up to $50 a day for food and lodging while they are in Annapolis.

If the recommendation survives the legislative session that begins next month, the commission's new pay and expense package will take effect in January, 1979, after the next elections.

According to the proposed timetable, the lawmakers would receive $16,000 a year beginning in January, 1979; $16,750 a year beginning in January, 1980; $17,600 a year beginning in January, 1981, and $18,500 a year beginning in January, 1982.

The speaker of the House and the president of the Senate would continue to receive an extra $5,000 a year under the proposal of the commission, which was created by a constitutional amendment to set salaries for members of the legislature.

George S. Wills, a commission member, said the proposed new salaries should be acceptable to the tax-paying public while providing lawmakers enough pay "to survive financially in a legislature when it is a part-time position."

The recommendation would make Maryland legislators the fifth highest-paid state lawmakers in the nation, according to commission date. Presently, their salaries rank 18th.

The last legislative pay raise was four years ago when the commission boosted salaries from $11,000 a year to $12,500 in 1971, the commission approved an increase from $2,400 a year to $11,000.