Four states, four classifications
Texas: for residential work, the contract form decides. The Texas Comptroller's publication on real property repair and remodeling distinguishes two structures. Under a lump-sum contract, it says, "you pay tax on all your supplies, materials, equipment, and taxable services when you buy them." Under a separated contract, "you give your suppliers resale certificates instead of paying tax on materials you incorporate into the customer's real property," and you then collect tax from the customer on the materials charge, which "must be at least as much as you paid for them." For residential work, labor is not taxable. For nonresidential work, the total amount charged is taxable, so the choice between the two forms does not change the result there. The page I read is marked revised 03/2007, so a reader should confirm the current version with the Comptroller.
Washington: tax on the whole price. The Department of Revenue's construction guide says contractors performing retail services, such as custom prime construction, must collect and remit retail sales tax on their total charges unless an exemption applies. The same guide classifies prime contractors, subcontractors and speculative builders separately, so a subcontractor should read the page for its own role before assuming the whole-price rule applies. The taxable amount includes labor, materials, profit, permits and subcontractor charges. The tax rate follows the jurisdiction where the work is done, and tax counts as collected only when stated separately on contract documents or invoices. For custom prime contracting, the invoice does not move the base; it documents the tax.
California: the contractor is usually the consumer. The Department of Tax and Fee Administration's guide describes lump-sum contractors as consumers of materials who do not bill customers sales tax on them. Its time-and-materials examples differ by what the contractor installs: a roofer is a consumer of materials and pays tax to the supplier, while a cabinet installer whose prefabricated cabinets qualify as fixtures is a retailer of them and owes tax on the billed price. Same industry, different trade, different treatment.
Ohio: real property versus installed equipment. An Ohio Department of Taxation presentation from November 2022 summarizes the framework. On real property construction contracts, the contractor is liable for sales or use tax on the cost of materials incorporated into the job. For contracts to install tangible personal property or business fixtures, the customer is taxed on materials and labor, and the contractor should collect tax on the invoice. The same crew can therefore fall on either side depending on what it installs.
Where the confusion actually comes from
Read together, the four sources show three independent switches. First, who is the consumer of materials: the contractor (California lump-sum, Ohio real property, Texas lump-sum) or the customer through resale (Texas separated, Ohio equipment installs). Second, whether labor sits in the tax base: not for Texas residential work, yes for Washington custom prime construction and Texas nonresidential work. Third, whether the paperwork matters: it decides the outcome for Texas residential work, and it proves collection in Washington.
A contractor working across state lines, or taking both residential and commercial jobs, can meet several of these combinations in a year. Reasoning from the sources, that is where mistakes arise: reusing one template everywhere, or assuming the supplier's receipt already settled the tax.
"Sales tax is considered collected only when stated separately on contract documents and/or sales invoices." (Washington Department of Revenue, Construction industry guide)
What an estimate and invoice need to separate
The practical rule from these sources is to record the facts a state could ask about, even where the rules do not require every one:
- Materials and labor on separate lines. Texas separated contracts and Ohio equipment installs require tax on materials or on both, so the split is the base.
- Tax as its own line, with the jurisdiction. Washington ties the rate to where the work is performed.
- Contract type stated plainly (lump-sum or itemized), and whether the property is residential or nonresidential.
- Subcontractor and permit charges identified, since Washington includes them in the base.
- Change orders documented with the same structure as the original.
One caution: separating lines does not change the result everywhere. A tax authority looks at the type of contract and the work, not just the layout of the page.
Tools that can help
A spreadsheet with a line-item template, kept up to date by a bookkeeper or CPA, handles this at low cost and keeps the accountant in the loop, which is where state-specific answers come from. Other accounting software is another option; check the vendor's documentation for how it handles construction sales tax.
Disclosure: Oppositioner and YOTU Invoices are owned by the same company, NexusVibe S.L. YOTU Invoices is invoicing software built for construction work. Its features page describes quotes organized into chapters, sub-chapters and items, a catalog of services and materials with saved prices, units and tax settings, and PDF invoices. Its own construction estimate template guide tells readers to "Separate labor, materials, equipment, subcontractors, permits or fees where applicable" and to check the transaction and location before stating tax treatment. On the vendor's pricing page (read 2026-11-06), the Starter plan is listed at $15.20 a month on annual billing ($182.40 a year), with a 30-day free trial and no credit card.
No software replaces state guidance. A tool can hold the structure and apply the tax settings a user enters; it cannot decide whether a given job is lump-sum or separated under a state's rules. That judgment belongs to the state tax authority's published guidance and a tax professional.
This article is general information, not tax or legal advice. Rules change and depend on the facts of each job; confirm with your state revenue department or a qualified tax professional.
