The surplus comes directly from personal income taxes, and while no one knows for sure what's led to the windfall, analysts say it could be a number of factors.
For example, some wealthy Californians might have moved some of their planned 2013 income into 2012 to beat the expiration of the Bush tax cuts. That would mean the state would get less revenue than it expects to next fiscal year.
Or perhaps, people whose rates went up under last fall's Proposition 30 paid their taxes in January instead of April. That would mean less money would come in over the next few months.
Or maybe the extra revenue simply comes from a growing California economy. Or some combination of the three.
Most budget watchers believe it'll take several more months - at least - before it's safe to draw any conclusions.
You can view the detailed budget numbers from the State Controller's office.