Companies registered in U.S. states are registered as foreign company in addition to domestic company. In the corporate world, “domestic" refers to the state in which the company is formed, and “foreign" refers to every other state. For example, a company formed in New York is a “domestic" company in New York and is “foreign" in every other state. Generally, a company formed in one state may transact business in another state only if it satisfies the requirements to act as a “foreign company” in that other state.

1. The Line of Foreign Companies’ Qualification and Registration
   
   A corporation must register as a foreign company when it is deemed to be ‘transacting business’ or ‘engaged in business activity’ in a particular state. According to the Commerce Clause of the United States Constitution, states are permitted to impose qualification or registration requirements exclusively on foreign companies that are involved in intrastate activities. States do not have jurisdiction to prohibit foreign company from engaging in interstate commerce within their states, and therefore do not have the power to compel the subjects of such companies to qualify or register for the purpose of doing business within their jurisdictions.
   
   Many statutes delineate activities that are not considered to constitute intrastate business operations. For instance, the Model Business Company Act (MBCA) provides an extensive enumeration of activities that are exempt from the definition of doing business. Such activities encompass participating in litigation, conducting meetings, maintaining bank accounts, owning property, and engaging in sales through independent contractors within the state.
   
   
2. The Requirements of Foreign Companies’ Registration
   
   When the level of business activity activates the provisions applicable to foreign companies, the entity is obligated to adhere to a range of requirements. According to the conventional "qualification" statutes, the company must obtain a "certificate of authority" or "permit to operate” from the secretary of state in the jurisdiction where it intends to operate. To secure this certificate, the company is required to submit information akin to that found in its articles of incorporation and must demonstrate that it is in good standing in its state of incorporation. This includes evidence of compliance with tax obligations and the submission of annual reports, with the certification being issued by the secretary of state of the home state.
   
   Furthermore, as with the company at home state, the foreign company must designate a registered agent and maintain a registered office within the state. Additionally, the company is obligated to remit filing fees, submit annual reports, and may be liable for state taxation. According to the recent "registration" statutes, the foreign company is required to submit a "foreign registration statement" to the Secretary of State, which contains information analogous to that necessary for obtaining a certificate of authority under the qualification statutes.
   
   
3. The Outcomes of Failure to Register in a Foreign State
   
   According to contemporary legal perspectives, the lack of foreign company qualification or registration does not invalidate the actions of a company, thereby rendering its contracts legally binding. However, a foreign company will be prohibited from pursuing legal claims within the state until it has completed the qualification or registration process. Additionally, in certain states, the foreign corporation that failed to qualify or register may also face civil penalties.
   
   According to the internal affairs doctrine, the governance of a company's internal relationships is determined by the law of the state in which the company is incorporated. Consequently, if a company incorporated in Delaware is authorized to conduct business in California and faces litigation in that jurisdiction, the California court will apply Delaware law concerning matters of internal affairs.
   

Reference:
[1] Richard D. Freer. The law of corporations in a nutshell. West Pub. Co, 2020.