A foreign-owned US single-member LLC generally files Form 5472 attached to a pro forma Form 1120 every year it has a reportable transaction with its owner - and capitalising the company or paying its formation fee counts. The failure-to-file penalty starts at $25,000 and applies even when the company is dormant. Whether you owe US income tax is a separate question, decided by effectively connected income rather than by the filing obligation.
Answer the questions to identify filing and tax issues that may need professional review. This tool does not calculate tax owed.
Two different questions
Owing US income tax and having to file a US form are separate questions. Many foreign-owned single-member LLCs owe no US income tax, yet still must file Form 5472 with a pro forma Form 1120 because they had reportable transactions. Missing that filing - even on a dormant company - is what triggers the $25,000 penalty.
US income tax itself turns on effectively connected income: whether your activity rises to a US trade or business through an office, employees, a dependent agent or inventory. That is a facts-and-circumstances test, so treat this tool as a map and confirm your specific case with a qualified professional.