Alarm Permit
Alarm Permits in Unincorporated Tarrant County Go Through the Sheriff
Put a monitored burglar alarm on a place outside any city's limits in Tarrant County and the permit for it is a Sheriff's Office matter. The Sheriff regulates alarm permits for unincorporated Tarrant County and issues them directly. The permit runs a year, and a renewal notice goes out in the mail before it lapses.
The trap is assuming the county page covers you when your address is actually inside a city. It usually doesn't. Fort Worth, Arlington, and plenty of other Tarrant cities run their own alarm programs with their own permits and false-alarm fees. For a genuinely unincorporated address, square away the application, fee, and renewal with the Sheriff's Office before the monitoring company switches the system live. An unpermitted alarm can mean a slower response when it actually trips.
Source to confirm: Tarrant County Sheriff's Office - Programs