More than four months after Dominion Energy Kewaunee Inc. and the town of Carlton announced agreement on the assessment of the former Kewaunee Power Station nuclear plant, the parties are still working on a plan to reimburse the company for about $12 million in property taxes.

Dominion, which argued the plant was worth nothing but offered to accept a $10 million assessment, sued in 2015 after paying a property tax bill based on the town’s $457.4 million assessment. A second suit was filed over the 2016 assessment of nearly $469 million.

Although the company waives its right to seek a refund of the town’s portion of those refunds, it is asking the county, Kewaunee School District and other tax entities to reimburse what is now conceded to be an overpayment of its property taxes.

The agreement was signed in January, and in February the parties received a 60-day stay while they worked out the mechanics of the refund. The company has agreed to allow a 10-year payback period to lessen the burden on each municipality or school district.

The 10-year chargeback plan still needs to be approved by Judge D. Todd Ehlers, who is hearing the case, and the state Department of Revenue must accept the plan as well.

Ehlers OK’d an additional 30-day extension in early April, and on April 20 he approved an interim order that sets the $15 million assessment as the final determination while other issues are being worked out.

The interim order was needed to give the state Department of Revenue sufficient time to stabilize state school aid for the Kewaunee School District for the 2017-18 school year, according to court documents. An attorney for the district estimated Kewaunee stood to lose $1.4 million in potential aid this year if the nuclear plant assessment was not resolved.

The plant closed in May 2013, and the county is faced with the phasing-out of the state utility tax that Dominion paid at the rate of about $750,000 a year. The tax is being cut 20 percent annually until 2019. Loss of those revenues led the County Board to impose a 0.5-percent sales tax that went into effect April 1.