The Columbus City School District will return nearly $1 million to Westerville City Schools over the next three years.

The Columbus City School District will return nearly $1 million to Westerville City Schools over the next three years.

The payback comes after an investigation into Columbus' billing for its Win-Win agreement -- the deal that allows suburban school districts to maintain their boundaries within the city of Columbus while sharing some commercial tax revenue from those areas with CCS -- revealed that some districts had been overcharged while others had been undercharged.

Over the years, the Westerville City School District had overpaid $933,000, said district Treasurer Bart Griffith.

The Westerville Board of Education approved an amendment to the Win-Win agreement at its Aug. 27 meeting that allows for the repayment of that money.

Under the agreement, Westerville will continue to pay about $1 million per year for the Win-Win agreement. For the current fiscal year, the district will be charged double because Columbus did not charge schools last year as the billing underwent review.

Money paid by Westerville, and other suburban districts who honor the agreement, now will go to the Educational Service Center of Central Ohio rather than directly to Columbus City Schools.

For each of the next three years, the Educational Service Center will return one-third of the money that's owed to Westerville.

The new agreement also calls Westerville and other districts participating Win-Win to review their bills before paying them annually, Griffith said. That is something that didn't happen previously because Columbus didn't share the complicated Win-Win formula.

"The way the process has been set up since the beginning of Win-Win, Columbus did the due diligence. Columbus figured out all the bills, and the other districts paid," said school board President Kevin Hoffman. "We're just following the letter of the law in paying for this."

The errors were found after a team of suburban districts, including Westerville, called for a review of past payments.

The repayment schedule will take Westerville through fiscal year 2015, Griffith said. In 2016, the 26-year-old Win-Win agreement will be up for renewal and will need the approval of Westerville and other participating school boards to continue.

"Between now and then, it would be my assumption, that we would do a study to see if this is something we do want to do going forward," Griffith said.

The Win-Win agreement was approved in 1986 to allow suburban school districts to protect their boundaries from being annexed by Columbus City Schools.

When cities annex land, their school districts general expand with them, but for decades, the Columbus City School District maintained static boundaries while the city of Columbus continued to grow.

In the early 1980s, the Columbus City School District began threatening to take over the tax-rich portions of other school districts that fell within the boundaries of the city of Columbus.

About 40 percent of the city of Columbus lies within suburban school districts.

To protect their territories, suburban schools negotiated the Win-Win agreement with Columbus City Schools.

The agreement stated that Columbus City Schools would not seek the transfer of suburban district territory in exchange for a portion of the taxes for commercial properties within Columbus city limits.

Annual payments were capped at $1,050,000, and Westerville typically has paid around $1 million in recent years.