To pay for the “once-in-a-lifetime” proposal, the state expects new revenue from conforming to federal tax changes and internet sales tax legislation, along with it being a “generally positive revenue year,” a spokeswoman said. Both the At-Risk Add-On and per student increases would come from projected increases in state lottery revenue.

Secretary of Finance Aubrey Layne said after Northam’s proposal that only about a third of the projected $150 million in new revenue through the internet sales tax would be available to the state’s general fund. Layne said legislators will also need to conform the state’s tax laws to the new federal code so taxpayers and their accountants can prepare 2018 tax year returns that reflect the Tax Cuts and Jobs Act that President Donald Trump signed last year.

“Conformity is where we start,” Layne said. “If we don’t conform, it’s going to be a real nightmare.”

The state is projecting a $594 million windfall from federal tax reform.

With new revenue coming into the state and tax collections on the rise — revenue collections are up 4.5 percent this year — now is the time to increase K-12 spending, officials and analysts said.