How much does your school spend, on average, per student?

Most principals and administrators can’t answer that question. But changes brought on by the Every Student Succeeds Act means they will soon have to.

“Starting December 2018, districts receiving Title I funds will have to start accounting for all expenditures at the school level,” said Michael Griffith, school finance strategist for the Education Commission of the States, at a recent conference for education journalists.

ESSA requires states to report per-pupil expenditures for every local education agency and school in the state on annual report cards. But in the vast majority of districts, spending is accounted for at the district level. Average teacher salaries, average per-pupil expenditures — they’re all calculated districtwide.

This provision of the new Elementary and Secondary Education Act didn’t get much attention in the debate over its passage, but it will amount to a significant change for many districts all over the country. Still, Marguerite Roza, director of the Edunomics Lab at Georgetown University and senior research affiliate at the Center on Reinventing Public Education, says the new requirements are a natural evolution from No Child Left Behind, when the school was identified as an important unit for measuring student outcomes.

Because of the way NCLB required states to report assessment results — by school as well as district — the diversity in student achievement within districts was not obscured by averages. Soon, the same will be true for spending in addition to test scores.

Roza’s research has found considerable disparities within districts when it comes to spending. Often, that is because more senior teachers who have higher salaries concentrate in certain schools — those with lower concentrations of students in poverty, for example. And because salaries and benefits make up the lion’s share of school expenses, that makes a big difference in per-pupil spending.

Right now, one way districts claim to be fair is by assigning an equal number of teachers to schools based on the number of students they’re serving. If one school has 10 veteran teachers and another has 10 newbies, the first school will be spending far more per student — even though, when it comes to record-keeping, it is only obvious that both schools have the same student-to-teacher ratios.

While some states and districts say the new requirements are overly tedious, if not impossible, to implement, Roza says ESSA will not require a change in accounting, just a change in the way officials slice the numbers. “It’s not that the data doesn’t exist,” Roza said. “Most districts know where their teachers work. They write them paychecks. We know how much we’re spending on salaries by school.”

The difference will be combining that dataset with others that may be on different computers or in different systems. States will also have to decide how districts should divvy up the cost of central office expenses, bulk technology purchases, and transportation. That might be hard, but Roza is already helping convene a working group of states and districts to develop a set of best practices when it comes to making these decisions.

And there is a powerful opportunity behind this reporting change.

If districts want to use their newly organized data as a tool for improvement, they can compare school-level expenses with student achievement and identify outliers. How well are schools serving their student populations, considering the amount of money they’re spending?

“That’s a new question — Are we leveraging our dollars to get the most for our students?” Roza said. “And right now, they can’t answer that.”

She recommends districts get ahead of the reporting deadlines to get a handle on their internal numbers. Beyond being a useful tool, the new reporting requirements will bring funding disparities into sharp contrast, whether they’re because of concentrations of veteran teachers or school-specific programs that end up boosting expenditures. Regardless of why they exist, administrators should not be caught off guard the first time these disparities show up on state report cards.