The starting point
A US LLC with one owner is, for federal income tax, a 'disregarded entity': the company itself pays no income tax, and its income is treated as the owner's. For a foreign owner the question is therefore not 'does the LLC pay tax' but 'is this income taxable in the US for me'.
When the income is US-taxable
A non-resident pays US federal income tax on income that is effectively connected with a trade or business in the United States. In practice that means real activity in the US: an office, staff, a dependent agent, or work physically done there. Services you perform from outside the US are generally foreign-source income and fall outside US income tax, even when your customers are American and the money lands in a US bank account.
Selling goods is less clear-cut. Inventory in US warehouses, people acting for you in the US, or where the sales are concluded can all point towards a US trade or business. If your country has a tax treaty with the United States, the treaty test is usually whether you have a permanent establishment in the US.
Passive US income
Dividends, interest, rents and royalties from US sources are taxed differently: usually by withholding at 30%, often reduced by a tax treaty. The payer withholds it before the money reaches you.
What you file even without US tax
Every year: Form 5472 with a pro forma Form 1120. If there is US-taxable income, also a personal Form 1040-NR (which needs an ITIN). These are information and tax returns at federal level; the state where the LLC was formed has its own annual report or fee, if any.
Multi-member LLCs
An LLC with two or more owners is a partnership for US tax. It files Form 1065 every year with a Schedule K-1 for each member. If it has US-taxable income, it must withhold tax on the share of foreign members and pay it to the IRS during the year.
State taxes and sales tax
States generally follow the same idea for income tax: without activity in the state, there is usually nothing to pay there. Sales tax works differently. It is charged on sales to customers in a state once you pass that state's threshold, commonly $100,000 of sales into the state in a year, and digital products are taxable in some states and not in others. Marketplaces such as Amazon and Etsy collect it for you on their own platforms.
Your home country
Paying no US tax does not mean paying no tax. Your home country decides how it treats a US LLC: some look through it and tax you on the profit directly, others treat it as a foreign company. Ask a tax adviser at home before you start trading through the LLC.
Frequently asked
My customers are American. Is my income US-taxable?
Not because of where the customers are. What matters is where the work is done and whether you have a business presence in the US.
Does having a US bank account make my income taxable in the US?
No. Where the money is kept does not decide where it is taxed.
Do I need to file anything if the LLC owes no US tax?
Yes. A foreign-owned single-member LLC files Form 5472 with a pro forma 1120 every year, also without tax due.
This guide is general information, not legal or tax advice. Rules and fees change; check your own situation with a professional.