Even if you work for a non-registered company, you can take a letter of appointment and get it signed by the owner. Major risk is that they do not have binding to give you notice before firing but that is even with registered company. You are also free to leave any time.
A company cannot come into existence until it gets registered. But no such obligation has been imposed for firms by the Indian Partnership Act, 1932. If a firm is not registered it does not cease to be called as a firm, it still exists in the eyes law.
No member of an unregistered firm can enforce his rights under the partnership contract against either the firm or any present or past member of it, nor can the firm sue its customers on their contracts.
In simple terms, an unregistered company is a business that is not covered under the provisions of the Companies Act 2006. Unregistered companies can be sole traders, where there is a single owner, or partnerships, where two or more people agree to operate the business for profit.
The sole proprietorship is the simplest legal structure for owning your own business. A sole proprietorship is a one-person business that is not registered with the state as a corporation or a limited liability company (LLC).
Registration of a partnership firm is not mandatory under law. The Partnership Act,1932 provides that if the partners so desire may register the firm with the Registrar of Firms of the state in which the firm’s main office is situated.
Reference: The Partnership Act,1932