RICHMOND, JUNE 13 -- Gov. L. Douglas Wilder announced today that Virginia tax collections are expected to fall another $100 million short of the official forecast when the 1990 fiscal year ends in two weeks, forcing a new round of belt-tightening for state agencies.

For the third time in six months, the state's financial officers have come out with bad news about revenue projections, with each forecast more dour than the one before.

Wilder and his financial aides said the latest announced shortfall, which brings the total to about $350 million, is not the result of a sluggish state economy -- they maintained that the economic outlook is generally fair -- but comes from a failure to predict accurately the impact of recent changes in the federal and state tax codes.

Wilder said he is directing state agencies to come up with savings so that Virginia's budget is balanced at the end of the fiscal year, as required by state law.

The squeeze also will throw the two-year budget cycle that begins July 1 out of kilter, Wilder predicted, if tax collections remain sluggish and some spending scheduled for this fiscal year is delayed.

"Let me put the matter simply: with the exception of an increase in taxes, everything is on the table" as far as budget cuts go, Wilder said.

Three months ago, Wilder and the General Assembly agreed on budget cuts of up to 5 percent in most state agencies for the next budget cycle. At the same time, legislators approved a $200 million rainy-day fund that the governor wanted, but which he said today he will not tap to erase the shortfall.

Wilder's secretary of finance, Paul W. Timmreck, said the shortage can be made up by applying a $38.7 million surplus from the current budget, unspent agency funds and $25 million set aside for non-general-fund programs. However, this would create a trickle-down effect as some of this money was obligated in the next budget cycle.

Republican Party officials were critical of today's announcement, saying they predicted all along that revenue forecasts from Wilder and Democratic legislators were too optimistic. The Joint Republican Caucus has called for various spending cuts, including a hiring freeze at most state agencies.

The caucus released a statement today suggesting that Wilder study the GOP's proposal "on the plane to Iowa," where the governor is heading next week for a two-day speaking tour that many believe is an attempt to lay the groundwork for a run for national office.

Timmreck said today that he and state tax officials are confounded by the sluggish tax collections, which are expected to grow about 3.5 percent this year for a total of about $5.8 billion -- the slowest increase in decades, Timmreck said.

"There is a systemic problem in our revenue-estimating methodology," he said.

The heart of the mystery, Timmreck said, lies with retirees and self-employed individuals who pay taxes in four installments. Revenue is down among this group, he said, perhaps because of rising sophistication in how to reduce tax liability.

In contrast to the GOP barbs, some Democratic legislators said today it is understandable that revenue projections can run aground when changes are made in the tax laws. "Hindsight is 20-20, but crystal-balling is never as good," said Del. C. Richard Cranwell (D-Vinton), chairman of the tax-writing House Finance Committee.

Senate Majority Leader Hunter B. Andrews (D-Hampton), who heads that chamber's finance panel, said he was pleased that the errant forecasts came from technical miscalculations and not from a slump in sales or other tax receipts that indicate the health of the economy. "I think the economy of Virginia is sound, and as long as the economy is sound we can handle" revisions in the budget, Andrews said.

But a key Northern Virginia legislator, Del. Warren G. Stambaugh (D-Arlington), said he isn't sanguine that the state's needs can be met without a tax increase, especially because of major spending initiatives that may be required to level educational disparities between rich and poor school districts.