That startling fact was part of a new report released last week by the Indiana Department of Education. It comes just a few years after the voucher program first launched.
And the number of those students heading straight into vouchers is likely to increase, even though one original intent of the program was to provide an alternative to parents and students for whom public school wasn't working.
The original voucher law required students to attend a full year of public school - first grade or higher - before they could obtain a voucher for private school.
Supporters of the provision had dual goals. They wanted students to try their local public schools - the backbone of the state's education system - before leaving them for a private alternative. Otherwise, some feared, the public schools could be gutted of the best students - with some of the most involved parents - before they ever learned whether public schools would fit their needs.
But secondly, the state's fiscal leaders were concerned about the financial viability of doing anything else.
Here's why: Roughly 8 percent of students in Indiana have historically attended a private school - most without ever entering the public school system. Until recently, the state didn't pay for the education of any of those students.
So as lawmakers started crafting the voucher plan, fiscal leaders had a big concern: What if the kids already in private schools started receiving vouchers? That would add to the cost of education in Indiana.
Enter the requirement that students attend public school first. That would mean vouchers could only go to those students whom the state was already funding. And because vouchers are generally worth about $4,000 and the state spends about $6,000 per student on public schools, the state would see some savings from the program - money that would be plowed back into the public schools.
But some voucher supporters pushed and won support for changes that have expanded vouchers to more students. Now, students who have a sibling in the program, who live in a school zone with an F rating or who receive special education services now automatically qualify for a voucher - as long as the family also meets income requirements.
That's why today, an increasing number of students who have never attended public school are receiving vouches.
According to a new Department of Education report, that cost the state some $16 million in additional funding during the last school year, prompting an outcry from voucher opponents, including Democrats.
"We're giving taxpayers the bait and switch," said Senate Minority Leader Tim Lanane, D-Anderson. "I don't think Hoosiers will be happy to know that their money isn't getting the bang for its buck they were promised."
Voucher proponents don't agree with the formula the state is using to calculate the $16 million. They say - and their arguments have merit - that the state is overestimating the number of students who would have gone to private school anyway.
"It is fair to presume most of the students ... have been diverted from the public school system, whether it can be documented or not," writes Jeff Spalding, an analyst for the Friedman Foundation for Educational Choice, which supports the program.
His calculations show that the state is still saving money from vouchers.
Regardless of who's right in today's argument, the percentage of voucher students who've never attended public school is likely to keep growing - especially if lawmakers further loosen voucher eligibility, which seems probable.
It's up to fiscal leaders to get a handle on whether that will cost the state or save the state money. The answer will be crucial to budgeting in future years - no matter what side of the voucher debate those leaders support.
Lesley Weidenbener is executive editor of TheStatehouseFile.com, a news service powered by Franklin College journalism students and faculty.