If you are a landlord, you are certainly taking a renter’s security deposit at some point. You may call it a damage deposit, security deposit, or just plain extra rent. In most cases, you will have to return all or some of it back to the renter at some point. And you have to return it correctly.
If you are going to be sued as a landlord, this is the number one reason why you will be sued, and you will likely lose.
States have various laws on how the deposit is supposed to be kept and how it must be returned. Here is how I do it in Minnesota.