SaaS Platforms and Borderless Sales
You run a software company outside the United States and a growing share of your revenue comes from U.S. customers. Your invoices all say the same thing: monthly subscription. U.S. tax law does not accept that description. Before anyone can tell you what is taxable, the revenue has to be characterized, and software revenue has at least four possible characters.
Characterization comes before everything else
Sourcing rules, withholding obligations, and treaty articles all attach to a type of income. A payment that is a royalty is sourced by where the intangible is used, may be U.S.-source, and is generally subject to withholding at the source. A payment for services is sourced by where the services are performed. A payment for a sold copy of software is sourced under the rules for sales of property. Same money, three different answers.
So the first task is not to ask whether you owe U.S. tax. It is to determine what you are selling, in the terms the regulations use.
The four buckets in Treas. Reg. §1.861-18
Treas. Reg. §1.861-18 governs transactions involving computer programs and digital content. Paragraph (b)(1) sorts every such transaction into one of four categories: a transfer of a copyright right in the digital content, a transfer of a copy of the digital content (a copyrighted article), the provision of services for the development or modification of the digital content, or the provision of know-how relating to its development.
A copyrighted article
This is the ordinary case where the customer receives a copy and gets no right to exploit the copyright. Under paragraph (f)(2), whether the transfer of a copyrighted article is a sale is decided "on the basis of whether, taking into account all facts and circumstances, the benefits and burdens of ownership have been transferred." If they have not sufficiently transferred, the transaction is a lease rather than a sale. A perpetual license to install and use, with no right to reproduce for distribution, generally lands in this bucket. Note what it is not: it is not a royalty.
A copyright right
This is the case where the customer receives a right to exploit the copyright itself, such as the right to reproduce and distribute copies to the public, or to prepare derivative works. Here the question is whether all substantial rights have passed. The regulation provides that a transfer of a copyright right that does not constitute a sale or exchange because not all substantial rights were transferred "will be classified as a license." A license generates royalty income. That single line is where most withholding exposure in software originates.
Services and know-how
Development or modification work performed for a customer who takes ownership of the resulting copyright is treated as the provision of services. Know-how is narrower than it sounds and requires information subject to trade secret protection and confidentiality conditions.
Access rather than a copy: the cloud rules
Most modern SaaS does not fit any of the four buckets cleanly, because the customer never receives a copy. Treasury addressed this. Final regulations published in January 2025 added Treas. Reg. §1.861-19, which defines a cloud transaction as one through which a person obtains on-demand network access to computer hardware, digital content, or other similar resources. Downloading digital content for permanent storage and offline use is not a cloud transaction.
The operative rule is short: a cloud transaction is classified as the provision of services. Not a lease, not a license, not a royalty. Where an arrangement has multiple elements, the regulation applies a predominant character test, looking to the primary benefit or value of the transaction to the customer where that is reasonably ascertainable.
Two limits on that rule are easy to miss. First, §§1.861-18 and 1.861-19 apply only for the purposes enumerated in the regulations, which include subchapter N and chapters 3 and 4, along with a specific list of Code sections. They are not a general-purpose definition for every question in U.S. tax law. Second, these regulations classify income. They do not source it. Treasury issued proposed sourcing rules for cloud transactions at the same time, built on a formulary approach weighing research and development, employee, and tangible asset costs. Those rules remain proposed rather than final, so cloud sourcing continues to run through the general rules and the facts.
Where the characterization sends you
| Character | Source rule | Practical driver |
|---|---|---|
| Services, including a cloud transaction | IRC §861(a)(3) and §862(a)(3) | Where the labor or personal services are performed |
| Royalty from a license of a copyright right | IRC §861(a)(4) | Where the property or right is located and used |
| Sale of a copyrighted article held as inventory | IRC §861(a)(6), §862(a)(6), §863, via §865(b) | Title passage, or production activities if you produce it |
| Sale of a copyrighted article not held as inventory | IRC §865(a) | Residence of the seller |
Two overrides sit on top of the table. IRC §865(e)(2) sources a nonresident's sale of personal property to the United States when attributable to a U.S. office or fixed place of business. And IRC §864(c)(4)(B)(i) treats foreign-source royalties from intangibles as effectively connected where they are derived in the active conduct of a U.S. business carried on through a U.S. office.
Withholding is where the theory becomes cash
If a U.S. customer concludes it is paying a royalty to a foreign person, IRC §1441(a) and §1442 direct it to deduct and withhold 30% of the gross payment. It will do this whether or not you agree with the characterization, because the liability for under-withholding falls on the payer.
Three documentation points follow. A treaty claim reducing that rate is made on Form W-8BEN-E and depends on qualifying under the treaty, including its limitation on benefits article. A claim that the income is effectively connected is made on Form W-8ECI; Treas. Reg. §1.1441-4(a)(1) exempts effectively connected income from §1441 withholding where the withholding agent can reliably associate the payment with a valid certificate, and the same regulation presumes income is not effectively connected absent a reliable claim. A treaty-based return position is separately disclosable under IRC §6114 on Form 8833, with a penalty under IRC §6712 of $1,000, or $10,000 for a C corporation.
An illustrative contrast. A foreign company licenses source code to a U.S. platform for redistribution and receives $400,000. If that is a license of a copyright right, the payer may treat it as a U.S.-source royalty and withhold $120,000 on the gross. Restructured as a subscription under which the U.S. customer accesses hosted software and receives no copyright right, the same commercial arrangement is a cloud transaction classified as services, and services income is sourced where the services are performed. The numbers are illustrative. The lesson is that the contract language, not the invoice label, drives the result.
Where your people and machines sit
Characterization answers what the income is. It does not answer whether you are engaged in a U.S. trade or business. That question is factual under Treas. Reg. §1.864-2(e), and it turns on whether U.S. activity is considerable, continuous, and regular.
For a software business, four facts carry most of the weight. Where the engineering and support work is actually performed, since services income is sourced to the place of performance under §861(a)(3). Whether any U.S.-based person can negotiate or conclude contracts for you, which is the trigger in Treas. Reg. §1.864-7(d)(1). Whether you have space in the United States that is at your disposal, which Treas. Reg. §1.864-7(b) treats as a fixed facility through which business may be carried on. And whether U.S. contractors are functioning as an extension of your operation rather than as independent businesses serving many clients.
Server location is a fact in this analysis, not a rule that decides it. There is no provision that makes rented rack space determinative on its own, and no provision that makes it irrelevant. Treat it as one input among the four above.
State sales tax is an entirely separate regime
Nothing above touches state taxation. There is no federal sales tax. Sales and use tax is imposed by states, and its reach was reset by South Dakota v. Wayfair, Inc., 585 U.S. 162 (2018), which overruled the physical presence requirement and allowed states to impose collection duties on remote sellers meeting economic thresholds. A foreign seller with no U.S. presence at all can have a state sales tax collection obligation while owing no federal income tax.
Whether SaaS is taxable at all varies by state and by classification. Some states treat hosted software as taxable prewritten software, some as a taxable data processing or digital service, and some do not tax it. The thresholds also differ from state to state.
Two protections that operators reach for do not extend here. Public Law 86-272, at 15 U.S.C. §381, restricts state net income taxation only, and only where in-state activity is limited to solicitation of orders for sales of tangible personal property. It says nothing about sales tax and nothing about software delivered as a service. And an income tax treaty does not reach state taxes. The taxes covered article of a typical U.S. convention lists federal income taxes; the U.S.–Germany convention, for instance, applies to "the federal income taxes imposed by the Internal Revenue Code" and one federal excise tax. A no-permanent-establishment position is a federal position.
The sequence worth running
Take your three largest revenue lines and, for each one, read the actual customer agreement to determine which category in §1.861-18 or §1.861-19 it falls into. Then source it under the rule that matches that character. Then list every U.S.-located person and facility connected to delivering it. Then, separately and without reference to any of the above, look at where your customers are and check state sales tax registration thresholds.
Contracts written before anyone considered these regulations frequently characterize badly, and the fix is prospective drafting reviewed with your own attorney rather than a filing position invented afterward. The firm's cross-border diagnostic starts from the agreements for that reason. Related material sits under IRS exposure analysis.