Q: Do I need an interior design degree to run my own design firm?
I get asked this question, a lot. And the answer is: it depends. The necessity of a design degree for working in interior design could be as important as a Masters in Creative Writing to a writer, nice to have, but ultimately not necessary or it could be as important as a degree in Architecture, required to become a licensed architect. The importance depends on what you want to do with your degree (or lack of).
Getting a degree in interior design is different from being licensed (usually by NCIDQ) in interior design. You get licensed in interior design by taking a difficult exam (NCIDQ) after completing interior design coursework. The National Council for Interior Design Qualification (NCIDQ) says that a "formal interior design education is an essential foundation for a successful practice". Being licensed allows you extra privileges in some states to sign, seal, and/or permit. Which means that you can sign and/or seal certain documents for construction purposes and permitting. A good place to check the state licensing regulations is ASID's website.
If you live in a state that gives designers licensing privileges, it may be worth it to get a degree in interior design and take the exam. If you would like to be working on new construction and remodels it may be worth it to get a degree and take the exam (or get a general contractors license). If you'd like to work for another designer who requires degreed designers, it may be worth it to get a degree and take the exam. If you'd like to work in an area that clients prefer licensed designers, it may be worth it to get a degree and take the exam. If you are going to be working in commercial or hospitality design, you need to get a degree and take the exam.
However, you don't need an interior design degree to run your own business. You don't need to be an interior designer to run a design firm. You can hire people who have degrees and never do any design yourself. You could work with other professional, like architects and contractors who will be doing the construction documents and you're providing design direction. You could also only focus on the decorating part of design, the furniture and soft finishes that don't require a degree.
Being licensed will never hurt you, more knowledge and education are not harmful. But a design education is not cheap and I don't want you to spend a fortune on schooling when much can be learned by experience. Experience is not something that is negotiable when embarking on a career as an interior designer. I wholeheartedly think that to run your own design firm you need to work for another designer first. Preferably several. There is no shortcut to on-the-job training. Not even a degree can prepare you as well as working experience. (You may be interested in reading Working for Someone Else). Experience doesn't cost you several thousands of dollars in tuition.
There are skills that you need to have and either you get those through schooling or experience. Most skills can be learned just through experience and dedication to learning. Other skills must be demonstrated to the state and so they can give you a piece a paper and a few letters after your name. The path you take depends on where you want your interior design career to lead you.