Hello, and welcome to the community. It may be a good idea for you to enlist the help of a corporate attorney and accountant in your area for specific answers about your particular situation. They will be the most familiar and best able to provide accurate information about corporate laws and requirements in the states you're involved with.
Meanwhile, feel free to take a look around the forums, join in anywhere you feel comfortable, and feel free to tell us a little about yourself and your company at Introduce Yourself.
Partnerships and s corporations are pass through entities, in which the owners pay taxes on their income, not the partnership or corporation. Why would an LLC be different? A one member LLC, if a sole proprietor would file a personal income tax return in NJ and pay the tax. In this case, it appears that the parent company would file a return and pick up the pass through income from the sub and pay the tax.
A DE incorporated C-corp owns a SMLLC located in NJ. SMLLC has income tax nexus in NJ but doesn't need to file business income tax with NJ since it's a pass through entity. So does parent company need to file income tax return with NJ and is the parent considered doing business in NJ?