Sales Tax Nexus for Trade Businesses Operating Across State Lines
Why this matters
A trade business that crosses a state line creates real sales-tax exposure even before they finish the first job. The 2018 Supreme Court decision in South Dakota v. Wayfair killed the old "physical presence required" standard and replaced it with an economic nexus regime where 45 states (plus DC) now assert taxing authority over out-of-state sellers based on dollar thresholds, transaction counts, or in many cases simple physical presence rules that were always available to them. Trade businesses are particularly exposed because physical presence happens the moment a truck rolls across the border for a single job. A contractor based in northern Virginia who does 12 jobs a year in Maryland and DC, or a Kansas City plumber working accounts on both sides of the state line, can owe back sales tax, use tax, contractor's excise tax, and franchise tax in jurisdictions they never registered in. Audit recovery periods run 3 to 7 years depending on the state, which means a problem discovered today can have a six-figure exposure built up before you noticed.
The two-part nexus test
Nexus is created two ways:
Physical nexus (always applies, never went away). Triggered by:
- Sending an employee or owner across a state line to perform work, deliver materials, or sell.
- Storing inventory, tools, or materials in a leased warehouse, public storage unit, or a customer's site for an extended period.
- Owning, leasing, or renting any real property.
- Using subcontractors who work on your behalf in that state (in some states; "click-through nexus" extended to physical agents).
- Registering a vehicle, opening a bank account, or filing for a contractor's license.
A single day of work in a state typically creates physical nexus. There is no de minimis exception in most states for performing taxable services.
Economic nexus (post-Wayfair, varies by state). Triggered when a remote seller exceeds a threshold:
- Most common: $100,000 in sales OR 200 transactions per year (some states dropped the transaction prong: CA, NY, TX, WA among others use a sales-only threshold, typically $500,000).
- Threshold typically measured against the prior calendar year or the current year-to-date.
- Many states count gross sales (including exempt sales) toward the threshold, then require registration even if the registered seller's tax liability is zero.
Service businesses often clear economic nexus without realizing it because the dollar threshold counts all revenue from buyers in that state, not just taxable revenue.
What's actually taxable: labor vs materials vs services
The single biggest source of misunderstanding. Each state takes one of three approaches to construction/repair labor and materials, and the answer changes how you bill:
Approach 1: contractor as consumer. The contractor pays sales tax to the supplier when buying materials, then bills the customer a single lump-sum price (no separate sales tax line). The contractor is the taxable "end consumer" of the materials. States in this camp: CA (mostly), AZ, NV, NM (partially), GA, NC, SC (for residential), most northeastern states for real-property improvements. The contractor cannot give a resale certificate to the supplier.
Approach 2: contractor as retailer. The contractor buys materials tax-free with a resale certificate, then collects sales tax from the customer on the marked-up price of materials plus labor (or just materials, depending on the state). States: TX, FL, WA, KS, MI for many repair services, plus most commercial/repair work in mixed states. The contractor collects tax and remits to the state.
Approach 3: hybrid by job type. The state distinguishes between new construction (Approach 1) and repair/maintenance (Approach 2). NY, IL, OH, MN, WI, IA, NE are this style. A new HVAC install on a new home might be a non-taxable capital improvement, but a furnace repair on an existing home is a taxable repair service. The Form ST-124 in New York (Certificate of Capital Improvement) and equivalents in other states control this. Get the certificate from the customer in writing or you remit tax on the entire job.
The contractor's excise tax (SD, NM, HI, WV gross receipts tax) layers on top of regular sales tax in those states and is owed even when the underlying work is exempt.
Crossing the line between repair (taxable) and capital improvement (non-taxable) in NY, NJ, and other hybrid states is enforcement-rich. State auditors will reclassify capital improvement jobs as repairs if your invoice lacks documentation of the permanent installation, lacks a signed customer certificate, or describes the work in repair language ("fixed", "serviced", "patched"). Auditors get bonuses for assessment volume. Document every capital improvement contract with the work scope, customer certificate, and permit number. Without that paper trail you owe back tax + interest + penalty (typically 25 percent uncollected-tax penalty) on every job.
Common multi-state scenarios for trade businesses
The bordering-state job. A NJ plumber takes a Long Island job because a relative referred it. One day of work, $4,800 invoice. Result: physical nexus in NY. Required to register with NY DTF for sales tax, file (even zero) returns, plus likely owe NY State Unemployment Insurance contributions on the wages paid that day. Most contractors ignore this until they pursue collection on a NY invoice and discover they can't file in NY courts as an unregistered foreign entity.
The repair-vs-CI mismatch. A general contractor in Florida hires you for a "remodel" that the GC has invoiced as a capital improvement. You bill the GC labor only, no tax. Audit determines the work was actually repair (you replaced existing components, didn't add new ones), and FL assesses you for uncollected tax on the labor portion. Your defense (you relied on the GC's representation) typically loses.
References
- South Dakota v. Wayfair, Inc., 585 U.S. ___ (2018). The Supreme Court decision establishing economic nexus authority.
- Streamlined Sales and Use Tax Agreement (SSUTA), governing body of approximately 24 member states that share a simplified registration and remittance system.
- 4 U.S.C. Sections 105-110 (Servicemembers Civil Relief Act and associated multi-state taxation framework); 15 U.S.C. Section 381 (P.L. 86-272 protection against income tax for businesses solely soliciting tangible-goods orders - notably does NOT protect service businesses).
- State-specific publications: California Sales and Use Tax Regulation 1521 (construction contractors); New York Tax Bulletin ST-104 (contractors); Florida Rule 12A-1.051 F.A.C. (sales by contractors); Texas Comptroller Publication 94-105 (real property repair and remodeling).
- IRS Form W-9 and Section 6050W (1099-K reporting) - relevant to substantiating subcontractor independent-contractor status across state lines.
- Multistate Tax Commission Voluntary Disclosure Program (a multi-state alternative to single-state VDA, available for some state combinations).