Technically, no. There is no law or authority that says you have to have a business plan before you starting. But most people do because it's smart to know what you're doing before you start. You can lose a lot of time and money just guessing. Do you have to have a travel plan before you leave on a trip? No. Do you have to book flights and hotels? No. But would it be a good idea?�

Don't stress out about having a full formal business plan document, at least not at first. Do just enough to reduce the uncertainty and guide your startup with realistic steps and budgets and such. I strongly recommend you look at my site The Plan As You Go Business Plan site, which is entirely free, part of my book of the same name, published by Entrepreneur Press. �