A Polish company selling goods or services to customers in the US without a physical presence typically does not pay federal income tax there — this is determined by the still-active 1974 Double Taxation Treaty. State sales tax remains a separate issue, depending on thresholds established by each individual state.
An increasing number of Polish companies sell goods and services directly to American customers — through their own online stores, sales platforms, or standard orders for clients in the US. The question that sooner or later occurs to all of them is similar: do I have to pay tax in the United States? The answer depends on two completely different systems — federal income tax and state sales tax — which are governed by different rules.
“Trade or business” and effectively connected income
The US tax authority, the IRS, follows a simple principle: a foreign entity that conducts business in the US (known as a U.S. trade or business) pays tax on income effectively connected with that business — abbreviated as ECI (effectively connected income). According to the IRS definition, the sale of goods or services conducted directly within the United States qualifies as such activity, and the profit from it is taxed on the same terms as the income of US companies and citizens — at progressive rates, after deducting costs.
However, the word “in the US” is key. Sales from Poland to a customer in the States alone — without physical presence on the other side — do not in themselves make a Polish company a taxpayer subject to US federal income tax. An international treaty decides where the boundary lies.
The key is a “permanent establishment” — and the treaty still dates back to 1974
Poland and the United States have signed a double taxation convention. Pursuant to Article 8 thereof, the profits of a Polish enterprise are taxable solely in Poland unless the company conducts business in the US through a so-called permanent establishment — in which case the US may tax only that portion of the profit attributable to such establishment. Article 6 defines a permanent establishment as a fixed place of business: a branch, office, factory, workshop, or construction site lasting longer than 18 months. On the other hand, warehouses as well as places of storage, display, or delivery of goods belonging to the enterprise are explicitly excluded — even when maintained by the company itself. For sellers using Amazon FBA-type warehouses, this is an important clue: merely storing goods in an American fulfillment center does not, according to the letter of the treaty, constitute a permanent establishment.
Here arises a detail that is easy to overlook. The applicable convention with Poland dates from October 8, 1974, and entered into force on July 22, 1976 — despite a new treaty having been signed in 2013 intended to replace it. The latter never entered into force: the IRS page with treaty documents for Poland, updated as recently as May 7, 2026, publishes exclusively the 1974 text. Guides describing the “new 2013 treaty” as already in force are therefore misleading — in practice, the old rules still count.
Sales tax is a completely different, state-level matter
The absence of a federal tax obligation does not close the subject, however. State sales tax (sales tax) remains a separate issue, having nothing to do with the international treaty — it is levied by individual states, not the federal government.
Until 2018, the physical presence rule applied: a state could demand tax collection only from a seller that had an office, warehouse, or employees there. This was changed by the US Supreme Court ruling in South Dakota v. Wayfair on June 21, 2018 (case no. 17-494), which overturned this rule. The court upheld the right of the state of South Dakota to impose a tax collection obligation on sellers who deliver goods or services valued at over $100,000 to the state within a year or complete at least 200 separate transactions — regardless of any physical presence. Following this ruling, most states introduced their own economic nexus regulations, but thresholds, transaction calculation methods, and exceptions vary from state to state and are subject to change — there is no single universal threshold applicable across the entire United States.
What this means in practice
For a Polish company selling to the US, the practical picture looks like this: without a physical presence in the States — an office, own warehouse, employees, or a representative with the right to conclude contracts on behalf of the company — the obligation to pay US federal income tax typically does not arise because treaty protection applies. At the same time, upon exceeding the sales threshold in a given state, a separate obligation to register and collect sales tax may arise — independently of income tax.
For bookkeeping, opening a bank account, or registering on sales platforms, a company typically needs an EIN number issued by the IRS anyway — which we wrote about in the context of setting up an LLC in the US. Assessing whether a permanent establishment has been created in a specific case and in which states one needs to register for sales tax, however, requires an analysis of the individual situation — the sales structure, the method of storing goods, and the scale of turnover in particular states.
It is worth conducting sales accounting for the US from the very beginning with an accountant who knows the regulations of both countries — Polish tax and finance specialists can be found in the Polish Pages directory.
This material is for informational purposes and does not constitute tax or legal advice. Assessing the tax obligations of a specific company requires consultation with a licensed tax advisor familiar with US and Polish regulations.
