Two north Fulton cities are setting the stage to hold their own constitutional conventions of sorts.

When Johns Creek and Milton celebrate their fifth birthday this December, a group of residents will meet to rate how their government has been working and whether it needs to be adjusted.

Among the topics weighing on city leaders is wording that establishes a cap on the property tax rate -- language that makes a tax increase virtually impossible and affects the cities' ability to issue bonds.

Like Sandy Springs before them, Johns Creek and Milton capped their property tax rate when they incorporated in 2006. That cap, 4.731 mills, cannot be raised without approval from residents.

But wording in the charter makes it virtually impossible for that to happen because it would require more than 50 percent of the "registered voters" to vote for it in a referendum.

Other new cities, including Sandy Springs and Dunwoody, require only a simple majority vote in a special election to lift the cap on their tax rates.

"I think it's important and valuable the citizens have input," Johns Creek resident Karen Reetz said, adding the cap should be reviewed along with everything else in the charter.

At a work session this week, the Johns Creek City Council directed staff to begin the search for a consultant who can direct the process of selecting members of the charter commission.

"You need to have rules of governance, not just form this committee, but say this committee's going to be formed and here's how this it's going to function," City Manager John Kachmar said.

Council members must consider the composition of the commission, including the number of members, whether there should be a chair and whether there should be alternates, he said. Another issue is whether appointments should be made by each council member or whether nominees should pass a super-majority of the City Council.

Milton has not had any formal discussions of a charter commission, although City Manager Chris Lagerbloom said he has made the City Council aware of their obligations. He also has spoken with the legislative delegation to alert them to the fact they will need to appoint a representative to the panel.

Most likely, Lagerbloom said, the panel will consider the tax cap and whether it should be left alone or adjusted. He also said there are some administrative procedures relating to contracts that might be considered.