The Maryland and Virginia general assemblies will sit down with new governors next month and begin to consider again how the public treasury shall be spent.

In each state it should be painfully clear to the legislators from their experience of less than one year ago that good budget management, especially good revenue projections, are crucial to fair treatment of the taxpayers.

Both states found themselves with the same budget problem last year - expecting a serious deficit - and both behaved very differntly.

The Maryland General Assembly, at the urging of suspended Gov. Marvin Mandel, passed major tax increase in cluding a 25 per cent increase in the sales tax to 5 cents on the dollar. No new services were funded, but the assembly responded to executive warnings that the new levies were essential to maintain existing services.

On the south side of the Potomac, Virginia Gov. Mills E. Godwin showed every sign of willingness to approve new taxes to stave off what he predicted could become a budget deficit of more than $100 million by next June 30.

However, he knew better than to propose a general tax increase to the House of Delegates because all 100 members were up for election in the fall. So he had to settle for another 1 per cent reduction in state spending - on top of the 5 per cent he already had ordered - and such fiscal footwork as a speedup in sales tax collection from merchants and a $35 million loan from the highway trust fund.

Less than nine monts after taking these opposite approaches to their budget problems, Maryland and Virginia again have parallel budget situations - although it is not a deficit the two states face this year.

In Maryland, the $132 million sales tax increase is now expected to produce a budget surplus of almost exactly that amount. In Virginia, a projected surplus of about $75 million appears likely despite substantial increases in state employee salaries approved by the governor. Virginia officials are seriously considering rescinding the speedup in sales tax collections.

Presumably, everyone is happy about the turn of events except the Maryland taxpayer. A year ago, a Maryland famuly laying out $200 a month for clothing, appliances, toys, school supplies and carryout food - a growing portion of the family diet - was paying $8 a month for government when it made these purchases.

Assuming a 5 per cent inflation, the same family this year is paying $210 a month for the same food and merchandise but, on top of these purchases, is buying $10.50 worth of government. In flation plus the sales tax increase has raised the family's actual sales tax outlay by more than 31 per cent.

Given the reluctance with which the Maryland General Assembly voted higher taxes in its last session, it is certain the legislators would not have approved this enormous, and possibly permanent, transfer of private income to the public sector for any purpose other than avoiding a major curtailment of services. But now, Acting Gov. Blair Lee says he is looking for ways to spend the money and is not considering a reversal of the tax action.

Virginians have a rendency to look askance at what goes on in government north of the Potomac, but in this instance they ought to put aside smugness and recognize they were saved by an election. The Virginia legislators also ought to take a much more critical look at the governor's revenue forecasts and insist on a reasonable cushion in the budget to prevent a recurrence of last session's deficit scare.

This is all the more important in Virginia, because the state still operates on a two-year budget, a holdover from the days when the General Assembly met only once every two years. A cushion could take the form of a deliberate under-appropriation of estimated revenues. It could also take the form of a list of capital outlays or expendable programs that the governor would be required to cut before coming back to the General Assembly in mid-budget with suggestions that new revenues are needed.

The best custom, of course, is first class revenue projections by the state's fiscal officers. For the last four years, Virginia's top financial officer under the governor has been Maurice Rowe, secretary of administration and finance. Rowe began in state government as an agriculture specialist and knows the bureaucracy well. No one has ever suggested he is a public finance expert.

Gov. elect John N. Dalton back to more familiar turf as secretary of commerce and resources and replace him in the finance post with Charles Walker, now the state comptroller.

Walker is an accountant and former corporate executive with strong ideas about the need for good revenue projections and not much reverence for the way the state has done business in the past.

He ought to be able to improve on the past record in Virginia, but if he doesn't, he can probably find work in Annapolis.