This seems like such a simple question, but there are a lot of issues. I’m sorry, please bear with me.(Note: I assume you understand the requirements and limitations associated with S-Corp tax status, i.e. cannot have foreign owners, etc)First, do you already have a company and are simply trying to change its tax status? If so, then you just need to fill out IRS Form 2553 and send it in. Please coordinate with your CPA / Accountant, to make sure you’re doing this properly and in a manner that won’t complicate your circumstances within a given tax year.ORSecond, do you already have a LLC and your accountant told you that you need a S-Corp, and you’re thinking you need to change from a LLC to a S-Corporation? If so, then think again. A LLC can be taxed like a S-Corp, so there is no reason (except in very limited circumstances — please consult with a tax attorney or CPA) not to simply change the tax status of your LLC. See the instructions in the First Answer above.ORThird, you have no company, and want to start up a S-Corp? If so, then . . .Are you sure of the entity type? Note you can get S-Corp tax status with a number of different entities (i.e. Corporation, LLC, Professional Corporation, etc), so you want to FIRST PICK the best entity / corporate structure, and THEN SET the proper tax status. We have an entity chooser that is very smart (and even factors in Trump’s 2017 Tax Reform Act), it only takes a few minutes: Business Entity Selector Tool | Law 4 Small Business, P.C. (L4SB).Do you care about anonymity? If so, then you cannot go with a Corporation, you will need a LLC. And, not just any LLC, but an Anonymous LLC. If you are conducting business in a state that permits anonymity (i.e. AL, CO, DE, GA, IA, NM, VA, WY), then you can simply file for an anonymous LLC in that state, but if you operate anywhere else, then you need to get a more complicated structure (parent/child, where the child company is an operating company in the state you’re conducting business, which is owned by the parent structure which is an Anonymous LLC from one of the anonymous states that is acting as a holding company). Learn more: Maintain Your Privacy With an Anonymous LLC | Law 4 Small Business, P.C. (L4SB).Once you’ve figured out the above, then pick someone to help you form the company. I am an attorney, so I am biased. If you are going to be a sole-owner, then any reputable online company will be okay. If, however, you have multiple owners, you really owe it to yourself to hire an attorney or law firm to help you. The reason is, multiple owners means “partnership,” and as an attorney, I’ve seen horrific, bankrupting, heart-attack forming fights between family members, former friends, spouses, etc, fighting about their companies — many of them where the formation documents are just so poorly drafted it created significant problems trying to resolve disputes or deal with a problematic partner / co-owner. Only a law firm or attorney will be able to consult with you properly, and make recommendations on the best way to form a partnership. We charge about the same as “the other guys,”. Learn more: Form a Limited Liability Company (LLC) | Law 4 Small Business, P.C. (L4SB).Finally, once your entity is formed, don’t forget to obtain your FEIN and then file IRS Form 2553.Good luck to you! Larry.