You dont have to register a "company name" to be self employed. There are various possibilities open to you. First you need to decide what you want to do, will you be opening a shop, will you be offering a service, will you wish to trade under a name that is different to your own true name.
You can register as a sole trader with Revenue, trading under your own name. If you wish to register a business or trading name which differs to your own name, you must do this with the CRO, so it could be Mary Darcy T/A (trading as) Mary's Fashions or Mary's Book Shop or The Village Bakery. You may also wish to set up a limited company, but you will need at least two directors and one secretary (one person can act as director and secretary), you will need to incorporate the company, get yourself a memorandum & articles of association, have a share capital, have a registered office, file accounts annually with the CRO as well as Revenue obligations.
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