Henry County and Stockbridge are headed to mediation next month to resolve a dispute over the cost of county-provided police services for the city for the next five years.

The county has been providing police protection to Stockbridge for nearly four decades. Stockbridge is Henry County’s most-populous city and the only one of the county’s four incorporated cities without its own police force. Stockbridge accounts for 15 percent of the calls that come into the Henry County police department.

The county’s latest pact with Stockbridge ended in December and the two sides have been dickering over the new price tag and services ever since.

The dispute is not over the quality of service but the cost.

“The service has always been excellent,” Stockbridge City Manager Michael Harris said. “We feel we’ve been paying our fair and reasonable share for police service. We look forward to reaching a resolution within the coming weeks.”

A gap of roughly $400,000 to $700,000 stands between the two sides inking a new deal. The county says it must raise its fee to provide the same level of service, because it has been subsidizing the city to the tune of about $400,000 a year.

Stockbridge says it’s willing to pay that new rate if the county will absorb other expenses — primarily city court and security at city council meetings — it now pays separately. The county says any extra personnel and services will cost more.

Under the new contract, Henry is raising its base rate to $900,000 — a $400,000 increase — to continue providing its current level of service. The county now provides two officers on duty around the clock.

Stockbridge also wants the county to include in its new price the cost of three bailiffs and an investigator for city court sessions as well as two police officers for city council meetings - positions Stockbridge currently pays $250,000 to $300,000 a year outside of its contract with the county.

In addition, Stockbridge wants to add a third officer per shift by 2019 when the city’s population is expected to reach 30,000.

The county says adding a third officer per shift will cost about $444,000 a year.

As it stands now, “We’re (already) short $400,000,” Henry County Commissioner Blake Prince said, referring to Stockbridge’s current deal with the county. “They don’t want to pay for the extra services. So it’s headed to mediation.”

Retired Georgia Supreme Court Judge Norman Fletcher will mediate the case on Sept 8.

Here’s a breakdown of the numbers being tossed around:

What Henry County says it costs annually to provide police service to Stockbridge: $2.1 million.

What the county says Stockbridge currently pays annually: $1.7 million, with $1.2 million coming from county taxes on city residents and $500,000 coming from revenue generated from city taxes on city residents.

What Stockbridge says it currently pays annually: $2.3 million — $1.8 million comes from taxes levied by the county on city residents for police protection. The rest comes from revenue raised by city taxes on city residents.

This could be the last round of negotiations between the county and Stockbridge because the city is considering reviving its police force in the future. Stockbridge briefly considered restarting its police force in 2013.