The teacher retirement is the biggest of five statewide plans administered by VRS, with 146,000 active members. It also has the biggest unfunded liability at $12.3 billion, reflecting the assets and long-term obligations that are about 73 percent funded. That amount is $492,203 less than it was a year ago, reflecting a market return on investments of 12.1 percent in the last fiscal year.

James J. Regimbal Jr., a fiscal consultant to the Virginia Municipal League and Virginia Association of Counties, estimated that the reduced teacher pension rate could save about $17 million for the state and $26 million for local school systems.

Regimbal wasn’t surprised by the estimated revenue required to pay K-12 costs, which he said grew at less than both inflation and student enrollment. Aside from the salary increase, he said, “the prevailing costs have hardly grown at all.”

But new spending for public education is just one of the big factors that will drive the new biennial budget, along with the reforecast of Medicaid expenses, a constitutionally required deposit of $272.5 million in the state rainy day fund this year, and growing pressure to expand a new cash reserve fund to satisfy concerns reaffirmed this month by Standard & Poor’s, a national bond-rating agency.