By Dan Walters, Sacramento Bee

If you want your head to spin, try to figure out how much money we spend each year to educate California’s 6 million K-12 school students.

Official agencies and outside groups publish numbers, but they rarely agree. They either take their snapshots at different times or include different types of spending and/or different sources of financing.

Gov. Jerry Brown’s budget pegs the number at $63.4 billion during the 2012-13 fiscal year, but assumes that voters approve his sales and income tax increase measure, Proposition 30, on the Nov. 6 ballot.

If it fails, that budget number would presumably drop by $5.5 billion, unless he and the Legislature change their minds after the election.

With that caveat, Brown’s number appears to be fairly accurate because it includes income and outgo that other reporting agencies often ignore, such as federal funds (about $7 billion), state payments for teachers’ pensions ($1.2 billion) and the repayment of school-construction bonds ($3.3 billion). It’s also roughly in line with the Census Bureau’s annual report on school spending.

Why are accurate school-financing data important?

It’s because Brown focuses on school finance in his campaign for Proposition 30, and because wealthy civil rights attorney Molly Munger is pushing a rival tax measure, Proposition 38, whose proceeds would almost all go to schools.

Brown’s number, which assumes Proposition 30 passes, is about $10,500 per student, somewhere in the lower third among the states.

Were it to fail – its chances are about 50-50 – a contingency plan already in the law would cut schools by $5.5 billion, but only about half would be real-time operating funds ($400 per pupil), accomplished by counting bond service as state aid. The remainder would be further delay in repayment of money already owed to schools.

Conversely – and this is very tricky – were Proposition 30 to pass, it would interact with the allocation formula under Proposition 98, the state school-finance law. Schools would see very little, if any, increase in operational financing, at least during the plan’s early years, according to the Legislature’s budget analyst and the California School Boards Association.

Munger has repeatedly hit that point because her Proposition 38 would, if enacted, raise income taxes and devote nearly all its revenue to classroom spending – by as much as $2,000 per pupil per year when fully implemented.

However, were Proposition 30 to lose and Proposition 38 win – a very unlikely event, polls indicate – school spending cuts for 2012-13 would take effect, unless they are modified, while Proposition 38’s new money wouldn’t kick in until the following fiscal year.

Confusing?

Absolutely, but when you look at how school money is allocated within the state, it’s even more so.