Yes. Though your business is online, you may still need to register as a company that is "doing business" in Illinois. You may need to apply for authority to transact business in Illinois. However, that depends on the nature of your business and your legal entity. You say your business is "registered" but you don't say registered as what and where. Is it a Delaware Limited Liability Company (LLC), Nevada subchapter S Corporation (S-Corp), or Wisconsin sole-proprietorship for example? Are you an employee, owner or both? You should contact an attorney to help determine exactly what you need to file with the state of Illinois, especially since you "ship products" internationally.
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