These days, you need a permit for almost everything. This isn't just to make your life more difficult, it could mean the difference between being safe and putting your home and family in jeopardy. When in doubt...ask.
As a general rule, any type of home remodeling project requires a permit.
You can actually use this to your advantage while you are interviewing contractors. Just ask about the permit and carefully watch their reaction. A reputable contractor will appreciate your question and will perform work “above code” whether the permit is required or not.
The less reputable contractors are more prone to squirm a bit on this question. If the contractor you are interviewing shows signs of disrespect for the rules, that's a good indication you don't want them working on your home.