Market-Based Sourcing for Service Providers: Rules and Hierarchy

Market-based sourcing rules for service providers assign your service revenue to the state where the customer receives the benefit, not the state where your people did the work. Roughly 39 states now use this approach, and because most of them also use a single-sales-factor apportionment formula, the sourcing decision often determines the entire multistate tax bill.¹ Get the sourcing wrong and a single engagement can produce deficiency assessments, interest, and penalties in states where you have no office and no employees.

What Changed From Cost of Performance

The older cost-of-performance method asked where you incurred the greatest costs to deliver a service and sourced the revenue there. Market-based sourcing asks a different question: where did the customer receive the benefit? The Multistate Tax Commission’s Model Regulation IV.17 defines “delivered to a location” as the location of the taxpayer’s market for the service, which “may not be the location of the taxpayer’s employees or property.”²

Only about six states still rely primarily on cost of performance, and several of those apply market-based rules to specific industries.¹ If you sell services in more than one state, treat market-based sourcing as the default and confirm each state’s specific rule.

Sourcing to Individual Versus Business Customers

The MTC model splits the analysis based on who buys the service, and the split matters more than most taxpayers realize.

When you provide a service to an individual, source the revenue to the customer’s state of primary residence. If you can’t reasonably identify the residence, fall back to the billing address.³ A financial planner advising a retail client in another state sources that revenue to the client’s home state.

Business-to-business services are harder. The revenue goes to the state where the business customer actually receives the service, which the MTC model defines as “the location at which the service is directly used by the employees or designees of the customer.”³ A consulting firm that delivers a strategy report to a client with operations in five states has to work out how the benefit of that report is distributed across those locations. Defaulting to the client’s headquarters without any analysis is one of the fastest ways to get reassessed on audit.

The Five-Step Sourcing Hierarchy

States don’t expect perfect knowledge of every customer’s exact location, but they do require you to work through the methods in order. You cannot skip to the billing address because it’s easier. The hierarchy must “reflect an attempt to obtain the most accurate assignment of receipts consistent with the regulatory standards.”³

Determine the actual delivery location. For in-person services, this is where the work happens in the customer’s presence. For electronic delivery to a business, it’s where the customer’s employees use the output.
If exact delivery can’t be determined, reasonably approximate it. Employee headcounts, user counts by state, or the proportion of a client’s payroll in each state are common proxies.
If approximation isn’t feasible, source the receipts to the state where the customer principally manages the contract.
If the contract management location can’t be determined, use the location from which the customer placed the order.
Use the billing address only as a last resort.

A company that defaults to billing addresses when it has user-level data will not survive an audit challenge. The hierarchy exists to push taxpayers toward the most granular data they can reasonably obtain.

Intangibles, Licenses, and SaaS

Market-based sourcing reaches past traditional professional services. The MTC model’s definition of intangible property covers licenses, literary and musical compositions, contract rights, securities, and computer software.¹ Revenue from licensing gets sourced to where the licensee uses the property to generate value: a trademark licensed to a retailer is sourced to the states where consumers buy the branded products, while a patented process licensed to a manufacturer is sourced to the state where the production facility sits.

Software-as-a-service providers face a specific problem because users can be anywhere. When the platform tracks where users log in, that data drives the sourcing. When it doesn’t, the hierarchy falls back to the customer’s business address on file and ultimately to the billing address. SaaS companies that don’t capture user-level location data are at a real disadvantage on audit, because states will question whether the company made a genuine effort to source accurately before defaulting.

When These Rules Apply to You

Sourcing rules only matter if you have nexus in the state. Since South Dakota v. Wayfair overturned the physical presence requirement in 2018, states have been aggressive about reaching companies with no office, warehouse, or employee within their borders.⁴ Revenue alone can be enough.

The MTC’s factor presence nexus standard, which many states have adopted or modeled their rules after, establishes nexus when a company exceeds any of these thresholds in a state during the tax period:

$50,000 in property
$50,000 in payroll
$500,000 in sales
25% of total property, payroll, or sales⁵

State thresholds vary. Some set their own dollar amounts, and several apply economic nexus to gross receipts taxes and franchise taxes on top of income tax. The $500,000 sales threshold catches more service providers than you might expect: a mid-size consulting firm with a few large clients in a single state can cross it in one engagement. Quarterly monitoring of revenue by state is the practical way to know when a new filing obligation has been triggered.

Public Law 86-272 Almost Never Helps Service Providers

Service businesses sometimes assume federal law shields them from state income tax when they have no physical presence. Public Law 86-272 prohibits a state from imposing a net income tax when a company’s only in-state activity is “the solicitation of orders for sales of tangible personal property” that are approved and shipped from outside the state.⁶ The protection is narrow: it covers tangible goods and nothing else. Services, licensing of intangibles, and any transaction involving franchises, patents, copyrights, or trademarks fall entirely outside its protection.⁷ For any business whose revenue comes from services or digital products, PL 86-272 is essentially irrelevant.

Throwback and Throwout Rules

When you make a sale into a state where you don’t have nexus, that revenue isn’t captured in any state’s sales-factor numerator. Tax professionals call it “nowhere income.” About twenty states have throwback rules that prevent it: if you aren’t taxable in the destination state, the sale gets reassigned to the state where it originated, increasing that state’s share of your income.⁸

A smaller group of states uses a throwout rule instead, removing those sales from the denominator rather than reassigning them to the numerator. The mathematical effect is similar: your home state’s apportionment percentage rises. Failing to establish nexus in a destination state doesn’t necessarily save you tax. It may just redirect the tax to your home state at a higher effective rate.

Documentation That Will Survive Audit

Sourcing decisions are only as defensible as the records behind them. State auditors verify customer locations and sourcing methodology at the transaction level, and the burden of proof sits with the taxpayer. The MTC’s audit guidance puts it plainly: “it is the taxpayer’s responsibility to have adequate records to establish tax liability.”⁹ When records fall short, auditors issue estimated assessments based on the “best available information,” and those estimates rarely favor the taxpayer.

At minimum, your records should capture the customer’s location and the point-of-use information for each transaction. In practice that means keeping:

Customer contracts that identify the intended place of use, delivery location, or the customer’s operating locations
Invoices that reflect the service destination rather than only the billing address
User logs and access data for digital services, showing where users log in from
Internal methodology documentation explaining how you applied the sourcing hierarchy and which step you relied on for each customer or customer category

Most states set their assessment statute of limitations at three to four years from the filing date, but many extend it to six years or more when there is a substantial understatement of income, and some eliminate the limitation entirely for unfiled returns. A sourcing error can go undetected for years, especially if you didn’t realize you had nexus. A six-year retention period gives you reasonable protection against most audit scenarios.

The real financial damage in a sourcing dispute usually isn’t the penalties or interest. It’s the reapportionment. When an auditor moves a substantial block of revenue from a low-tax state into a high-tax state, the tax differential on several years of reassigned income can dwarf everything else. That is the scenario most companies underestimate.

Cleaning Up Past Exposure

Companies that discover they should have been filing in states where they have nexus have a choice: wait and hope no one notices, or come forward voluntarily. The second option is almost always better. The Multistate Tax Commission runs a centralized Voluntary Disclosure Program that lets a taxpayer resolve exposure in multiple states through a single application rather than approaching each state individually. There is no charge to participate.¹⁰

Under a typical voluntary disclosure agreement, you file returns and pay back taxes for a defined lookback period. In exchange, the state waives penalties and limits your exposure to that lookback window rather than reaching back to the first year of nexus. Interest on the unpaid taxes is still owed unless a state specifically waives it. The minimum tax liability for the MTC to process an application is $500 per state.¹⁰

The critical eligibility rule is that the state cannot have already contacted you about the tax type. If you’ve received a nexus questionnaire, filed a return, or been the subject of a state inquiry, voluntary disclosure is off the table for that state and tax type. The window closes the moment a state reaches out first, which is what makes early self-assessment worth the effort.

1
Multistate Tax Commission. Review of MTC Model Sales/Receipts Sourcing and Special Industry Regulations
2
Multistate Tax Commission. Model General Allocation and Apportionment Regulations – Section 17, Sale of a Service
3
Multistate Tax Commission. Review of MTC Model Sales/Receipts Sourcing and Special Industry Regulations – Section: General Allocation and Apportionment Regulations, Section 17
4
Supreme Court of the United States. South Dakota v. Wayfair, Inc., 585 US (2018)
5
Multistate Tax Commission. Factor Presence Nexus Standard for Business Activity Taxes
6
Office of the Law Revision Counsel. 15 USC 381 – Imposition of Net Income Tax
7
Multistate Tax Commission. Statement of Information Concerning Practices of Multistate Tax Commission and Signatory States Under Public Law 86-272
8
Multistate Tax Commission. Notes on Throwback Rule
9
Multistate Tax Commission. Sales and Use Tax Audit Manual
10
Multistate Tax Commission. Multistate Voluntary Disclosure Program