New York State's sales tax rules for contractors and construction companies are among the most complicated in the state's tax code — and the consequences of getting them wrong are among the most costly. The Department of Taxation and Finance audits contractors aggressively, and the assessments that emerge from those audits frequently run into the tens or hundreds of thousands of dollars.
This article provides a comprehensive overview of the sales tax rules every New York contractor, home improvement business, and construction company needs to understand. These rules apply statewide — from Long Island and New York City to upstate and the Capital Region.
While our office is based on Long Island, we represent contractors and construction businesses in NYS sales tax matters throughout New York State.
The NY critical distinction: capital improvement vs. repair, maintenance, and installation
Everything in New York's contractor sales tax law flows from one foundational distinction: whether the work performed is a capital improvement to real property or repair, maintenance, and installation work. The sales tax treatment of these two categories is completely different, and misclassifying jobs between them is the single most common source of contractor audit liability.
A capital improvement is work that adds value to real property, prolongs its useful life, or adapts it to a new or different use — and the improvement must become part of the real property. Classic examples of capital improvements include adding a room addition, installing a new roof, constructing a new garage, installing a central air conditioning system in a home that did not have one, or finishing a previously unfinished basement.
When a contractor performs a capital improvement, the tax treatment is: the contractor pays sales tax on materials purchased for the job (or purchases materials under a resale certificate and pays use tax), and does not charge the customer sales tax on the contract price. The customer pays no sales tax on a capital improvement contract.
Repair, maintenance, and installation work [ RMI ] — replacing a broken window, repairing a damaged roof section, servicing an existing HVAC system, painting a room — is taxed completely differently. The entire charge to the customer, including both labor and materials, is subject to New York sales tax. There is no labor exemption.
For a detailed discussion of how this distinction plays out in an audit context, see our article on sales tax audits for contractors and home improvement businesses in New York. For Long Island contractors specifically, see our guide on sales tax issues for Long Island contractors: Nassau and Suffolk County guide.
The NYS ST-124 capital improvement exemption certificate
When a contractor performs work that qualifies as a capital improvement, the proper documentation procedure is for the property owner to complete Form ST-124 — the Certificate of Capital Improvement — and provide it to the contractor. The contractor retains this certificate as documentation supporting the decision not to charge sales tax on the job.
In a DTF audit, the ST-124 file is one of the first things examined. A contractor who classified jobs as capital improvements but cannot produce completed ST-124 certificates for those jobs is in a vulnerable position. Auditors can and do re-classify undocumented capital improvement claims as taxable RMI work, resulting in assessments on the full contract price, including labor.
Every contractor in New York should have a systematic process for obtaining completed ST-124 certificates from property owners before beginning capital improvement work — and for retaining those certificates in an organized file for at least three years.
Purchasing materials: taxable or tax-free
How a contractor handles the purchase of materials depends on the type of work being performed. For capital improvement work, the contractor is the end user of the materials for sales tax purposes — the materials are incorporated into the real property. The contractor should pay sales tax on the materials at purchase.
For RMI work where the contractor will charge the customer sales tax on the full contract price, including materials, the contractor may purchase materials under a resale certificate (Form ST-120) and collect the tax from the customer on the full invoice. The contractor cannot purchase materials tax-free and then also fail to collect tax from the customer — the tax must be paid at one stage or the other.
When contractors perform a mix of capital improvement and RMI work, they need to track material purchases by job type and handle the tax accordingly for each job. This tracking requirement is an important compliance discipline that many contractors — especially smaller operations — do not maintain consistently.
New construction vs. existing structures
Work performed on new construction — structures that have never been occupied or used — is generally treated as a capital improvement regardless of the specific nature of the work. The installation of any systems, finishes, or components into a new building is part of the capital improvement of constructing that building.
Work performed on existing structures is where the capital improvement versus RMI analysis becomes essential. The same physical work — installing windows, for example — can be a capital improvement on one job and a repair on another depending on the context, the scope of the project, and how the work affects the value and useful life of the property.
NY Subcontractors: a frequently mishandled area
When a general contractor uses subcontractors, the sales tax treatment of the subcontractor's charges to the GC requires careful analysis. If the subcontractor performs taxable work — RMI work — and charges the GC, the GC may owe sales tax on those charges unless the GC provides the sub with a valid resale certificate indicating that the GC will resell the services (by incorporating them into the final taxable charge to the customer).
The mechanics of subcontractor relationships and sales tax are frequently mishandled, creating either overpayment or underpayment of tax. Getting these arrangements structured correctly from the outset — with clear documentation of the nature of the work and the tax treatment agreed upon — is far better than reconstructing the analysis in an audit.
Government contracts and exempt customers
Work performed directly for New York State, New York City, or other government entities may qualify for sales tax exemption. The government entity typically provides the contractor with an exemption certificate establishing its tax-exempt status. Contractors who do significant government work need to maintain complete exemption certificate files and understand the scope of the exemption, which does not extend to all materials purchased for the government job.
Nonprofit organizations, religious institutions, and certain other entities also hold sales tax exemptions. Contractors who accept exemption certificates from these entities need to verify the certificates are valid and retain them for the audit period.
Why work with an experienced New York sales tax attorney
NYS sales tax matters are not like federal tax issues. The New York State Department of Taxation and Finance has its own procedures, its own auditors, and its own enforcement playbook — and it moves aggressively. For contractors, the capital improvement versus RMI distinction is not a one-time analysis — it is a job-by-job determination that must be made correctly on every project. Having a New York sales tax attorney available for compliance guidance and audit defense is a sound business practice for any contractor operating in this state. Here is what an experienced New York sales tax attorney brings to the table:
Deep knowledge of DTF procedures. We know how auditors are trained, how the Civil Enforcement Division operates, and where assessments and enforcement actions can be challenged. Generic tax help is not sufficient here.
Direct negotiation with the Tax Department. We communicate with the DTF on your behalf from day one — protecting you from statements that can be used against you and positioning the case for the best possible outcome.
Personal liability protection. NYS sales tax is a trust fund tax. If your business owes it, the state can and will pursue you personally. An attorney identifies and limits that exposure before it becomes a personal financial crisis.
Knowledge of every resolution option. From installment agreements to Voluntary Disclosure to formal appeals — we know which path fits your situation and how to negotiate the most favorable resolution.
Local presence, statewide reach. Our practice is based on Long Island and focused exclusively on New York tax problems. We are not a national call center. When you work with us, you work directly with an attorney who knows New York State tax law from the inside.
Speak with a New York sales tax attorney
If you are dealing with a sales tax compliance question about your contracting business, a DTF audit notice, or an outstanding sales tax assessment, do not wait for the situation to escalate. The sooner you have qualified representation, the more options remain available to you.
Contact our office to speak directly with a New York sales tax attorney. While our office is based on Long Island, we represent businesses and individuals facing NYS sales tax problems throughout New York State — from New York City and Long Island to Westchester, the Capital Region, the Hudson Valley, and beyond. Call us or use the contact form at Tax Problem Law Center to schedule a consultation.