It's clear from property tax bills hitting mailboxes that residents in some cities in DeKalb County are paying more for county services while their counterparts in the unincorporated areas are seeing the same rates as last year.

What is not clear: Why DeKalb adjusted property tax rates for services like police, parks, roads and fire protection that cities can pay the county for or provide themselves, but not for those same services in the unincorporated area.

The move raised county taxes by as much as 15 percent for residents in some cities.

"I'm anxious to hear what they have to say," said Chamblee Mayor Eric Clarkson, who united with mayors from seven other DeKalb cities to formally request an explanation from the county. Atlanta did not join in the request.

A similar complaint in Gwinnett County prompted years of legal wrangling that only ended when the county agreed to pay its 15 cities $32 million for, in essence, double-taxing municipal residents.

The city-county dispute over tax dollars has also popped up in Fulton, where cities in the north have routinely threatened to sue the county. The issue could come to a head in Cobb next year, when its service agreement expires.

It was supposed to be different in DeKalb. County and city leaders congratulated themselves in 2010 when they agreed the cities could buy services a la carte.

That means, for example, that for police services cities could choose basic protection such as patrols, or advanced services that include access to SWAT coverage and county-owned helicopters.

The tax rate associated with each service appears on the county portion of tax bills — meaning property owners see any costs or savings.

This year unincorporated residents saw a 37 percent drop in their police tax rate, a drop that offset an increase in the general tax rate that all county residents pay to fund things like the jail or libraries.

Residents in the smaller cities of Avondale Estates, Clarkston, Lithonia and Pine Lake — which all pay for more expansive police protection — saw a 3 percent dip for police.

Meanwhile, rates in the larger cities of Chamblee and Decatur, which pay for more specialized police services, saw their rates jump 18 percent and 11 percent, respectively.

Budget documents show the county ended 2011 with a $14 million surplus in its police fund — money that it spent to lower the unincorporated rate for police in 2012.

But none of the county commissioners, charged by the charter with setting the tax rates, could explain the different rates for services.

Even members of the commission's budget committee admit they need a presentation from the county finance team to understand it. They have invited the mayors to that meeting, slated for Tuesday.

"Frankly, we have questions as well," said Commissioner Lee May, head of the budget committee.

It's not easy to simplify the complicated question of how much taxpayers actually pay.

Dunwoody, for example, opts out entirely from county police protection. But residents there still must pay for fire protection and general taxes, both of which went up for everyone this year.

The county part of a Dunwoody taxpayer's bill went up 15 percent, the biggest increase in DeKalb. County taxes for unincorporated residents stayed the same.

So did the final bill for Jim Mackesey, even though he lives in Dunwoody. That's because the county cut the assessment of his four-bedroom home facing the greens of Dunwoody Country Club — lowering his bill regardless of the tax rate.

"I'm not feeling bad, because I'm back where I was," the retired IBM executive said. "If I hadn't gotten that reduction in my assessment, I'd be madder than hell."

Whether DeKalb can stave off any possible legal action will depend in part on how it explains its calculations. Going forward, leaders from the cities also want DeKalb to consult the cities on the tax rates.

That would be yet another factor to add to a 2013 budget process already complicated by the pending creation of the city of Brookhaven and likely annexation of unincorporated land into Chamblee.

"We were all so proud we could stay out of court on this kind of thing," Chamblee's Clarkson said. "We want to believe we can continue to work in good faith."