Josh Cowen is a professor of education policy at Michigan State University. He has been involved in research on vouchers for two decades. He wrote the following article for The Houston Chronicle.

Every state has versions of Texas’ Snapshot Day: the time early in the school year when districts submit pupil counts to their state education agency. How many students go to school in each district determines how much money districts receive each year, as well as a variety of other services and programs.

Not every state is considering a school voucher program, however, and as the Texas Legislature debates that possibility (officially called an education savings account), details like pupil count are going to matter a lot more than either voucher supporters or opponents are considering right now.

Here’s how we know.

I’ve been studying school choice policy for two decades. That work includes official evaluations on behalf of state agencies, and more recent experience on the research advisory board for Washington D.C.’s federally required evaluation. I’ve also worked as a research partner to states and districts across the country. I know how little, seemingly inconsequential, technical details can have great impacts on how education programs function.

And I know those impacts can be costly — with taxpayers footing the bill.

Consider evaluations of voucher programs like the one before the Legislature right now. I’ve described elsewhere how these studies show catastrophic
academic harm to students who switch to private school with a voucher. That’s because vouchers tend to pay tuition, not at elite providers that don’t need the tax dollars, but at subprime schools needing the bailout — including those popping up to cash in on the new government subsidy.

Here’s something else those programs tell us: Although supporters often describe school choice as a long-term opportunity, the reality is that, for many kids, school choice is just a revolving door in and out of a new academic setting. And that’s especially true with vouchers.

Studies show that more than 1 out of 5 students give up their voucher every year. In some places like Florida that number is as high as two-thirds of voucher students leaving the program within two academic years. Similarly, the numbers publicly available from Indiana, Louisiana, and Wisconsin range between 20 and 30 percent annual student attrition.

These exit rates matter not only because they underscore the false promise vouchers give to at-risk students — switching from school to school is a well-understood marker of academic or economic duress — but because they imply a huge potential fiscal waste.

Voucher supporters say it’s easy: The “dollars follow the kid” (this already happens with public schools, which is why count days exist). But it’s not that simple. Public programs with price tags in the hundreds of millions of dollars never are.

Imagine a parent who spends all of the proposed $8000 of their voucher at a private school nearby. Let’s say that before the last Friday in October — Snapshot Day — she sees the school simply isn’t working for her child and withdraws him. Will that private school keep the money? Or will the “dollars follow the kid” immediately back to the public school?

Imagine that parent waits until the holiday season to make the change. And in January, she enrolls her child back in a local public classroom. Will that local school be forced to enroll her child — a refugee from the voucher program — on its own local dime for the rest of the year?

Do these answers change if instead of the parent deciding to remove her child, the private school has made that choice instead?

If the voucher school has asked or forced her child to leave — something the current legislation permits for any reason along with denying admission in the first place — will it keep her tuition dollars as long as it waits until after Snapshot Day to do so?

These 30 percent of voucher decliners aren’t just numbers. The studies from other states tell us they’re likely vulnerable: kids who are scoring lower on school exams, kids from lower income families, children of color, and children from single-mom households.

Senate Bill 8 only stipulates that parents must notify the state of their exit within 30 business days; it does not establish a process to recover those dollars. And even when state guidance on these questions is issued, who will enact them? The fiscal note on SB8 makes assumptions about staff and legal support to run the program, but the legislation itself is ambiguous on issues like tuition reimbursement, or even the authority that compliance officers have to recover state funds.

Details matter. The ballooning voucher budget in Arizona and controversial new roll-out in Arkansas warn us that making public policy by slogan — however clever “fund students, not systems” might sound — is no substitute for careful planning.

The revolving door of school voucher tuition is one such detail — one that not only affects taxpayers’ bottom-line, but more basic issues of equity and opportunity as well. The bottom line for SB8 then, based on the evidence in other states, is that school voucher-type programs are on average bad for kids and bad for taxpayers. Texas would do well to reject them now.