Considering a move? Here are the property tax rates in every Miami-Dade city.

Not that Opa-locka needs a reminder of bad news, but there’s this: Residents in that troubled city face the highest property-tax rates in Miami-Dade County.

A state summary of property-tax rates paid in cities show Opa-locka’s combined 2017 rate at 2.6 percent. That’s well above the average rate of 2.1 percent paid in Miami-Dade’s 35 municipalities and its unincorporated area.

The lowest rate can be found in one of Miami-Dade’s wealthiest enclaves: Key Biscayne, where residents pay a property-tax rate of just under 1.7 percent.

What’s at work? Local governments set their own tax rates, and those municipal taxes make the difference between being at the top of the list and the bottom of the list. The rates in this story combine all the property taxes a city resident pays, including the municipal property tax, the property tax set by the county school board, and countywide property taxes.

A prosperous real estate market certainly can help keep rates low: Key Biscayne’s properties have a combined market value of $10.9 billion, compared to just $1.1 billion for Opa-locka. Both have similar populations to serve: about 13,000 for Key Biscayne and about 16,000 for Opa-locka.

With Opa-locka’s government flirting with insolvency — the state has already taken over and there’s talk of dissolving the city — the higher tax rate offers another measure of the challenges faced by residents there.

The tax-rate list follows no set rule of thumb. While ritzy Key Biscayne enjoys the lowest tax rate, famously exclusive Golden Beach sits near the top with a rate of 2.4 percent. Wealthy beach cities of Aventura and Bal Harbour sit near the bottom, with rates below 1.8 percent. So does the suburban sprawl of Miami-Dade’s unincorporated area, which pays a special tax for municipal services provided by the county.

One big factor to keeping tax rates lower: vertical development. With denser populations, cities can pack multiple taxpayers into smaller areas, rather than having to service large swaths of properties spread out from suburb to strip mall.

A sewer pipe to a 50-unit condo is a lot cheaper than a sewer pipe going three miles, and serving the same amount of people.

Lazaro Solis, deputy property appraiser for Miami-Dade County

“A sewer pipe to a 50-unit condo is a lot cheaper than a sewer pipe going three miles, and serving the same amount of people,” said Lazaro Solis, deputy property appraiser for Miami-Dade.

Local governments don’t set actual tax rates; instead they approve “millage rates,” which is the amount of dollars charged for every $1,000 of taxable value. For this chart, we divided the millage rate by $1,000 to get a percentage. That’s the tax rate — the portion of a property’s value charged as a tax. Opa-locka has hit the state limit of 10 mills for municipal services. Key Biscayne charges just 3 mills.

The actual city tax rate accounts for about 29 percent of the average tax bill, according to the state figures for Miami-Dade. The property tax that Miami-Dade charges on all properties accounts for about 24 percent of the bill.

The highest chunk, 35 percent, goes to Miami-Dade’s school system. Those figures are based on averages of all the municipalities, and would vary from city to city. Another key factor is whether cities provide their own fire departments and libraries; in those that don’t, residents must pay special county taxes funding those services.