Where the line generally falls
The rule of thumb is that replacing something like for like usually does not need a permit, while changing or adding wiring does. Swapping a light fixture on an existing box is maintenance. Running a new circuit to it is not.
Requirements are set by the state electrical code and administered by your town's wiring inspector, so the safest answer for a specific job is to ask before starting rather than after.
- Generally needs a permit: new circuits, panel work, service changes, EV chargers, generators, remodels, hot tubs, outdoor circuits
- Generally does not: replacing a fixture, switch, or receptacle on existing wiring in the same location
Why unpermitted work causes trouble later
Skipping a permit saves a small fee and some scheduling. The cost arrives later, usually at the worst moment.
It surfaces during a home sale, when a buyer's inspector finds work with no record. It can complicate an insurance claim after a fire, where an insurer asks whether the work was permitted and inspected. And it transfers responsibility to you for whatever a future inspector finds behind the wall.
What the process actually involves
For a homeowner using a licensed contractor, the process is mostly invisible. The contractor files the permit, schedules the inspection, and attends it.
On larger work there are usually two inspections: a rough inspection before walls are closed, and a final inspection once devices and fixtures are in. On a remodel the rough inspection is the one that holds up every other trade if it is missed.
The offer worth refusing
If a contractor offers to skip the permit to save you money, understand what is being offered. The saving is small, and what you are accepting in exchange is the liability.
A licensed electrician should pull the permit without being asked, and should be willing to show you the license and certificate of insurance before starting.