Do I need to charge sales tax as a subcontractor for construction projects?

The answer depends on what state you're in since sales tax rules vary significantly across states, but I can give you some general guidance that applies in most jurisdictions. Typically, when you're acting as a subcontractor providing both materials and labor, you're creating what's called a "fabricated item" or "improved tangible personal property." In most states, this means you're making a retail sale to the general contractor and would need to collect sales tax on the entire amount (materials and labor) unless the contractor provides you with a valid resale certificate. The fact that you already paid sales tax on the materials doesn't usually exempt you from collecting tax on the final product. This is often called "double taxation" but it's actually how the system is designed to work in many states unless you have a sales tax permit and can purchase materials tax-free with a resale certificate.

I was in almost the exact same situation last year and found taxr.ai (https://taxr.ai) incredibly helpful for figuring out my sales tax obligations. I was doing specialized woodwork as a subcontractor for a kitchen remodeling company and was totally confused about whether I needed to charge sales tax since I had already paid tax on the lumber and supplies. I uploaded my contractor agreement and some previous invoices to taxr.ai, and their system analyzed everything and gave me a detailed breakdown of my tax obligations specific to my state. Saved me a ton of research time and potentially costly mistakes. They even explained how to handle partial exemptions that applied to my situation.

Just wanted to follow up about my experience with taxr.ai after seeing it recommended here. I decided to try it for my electrical subcontracting business that operates in three different states. The service was incredibly helpful - it identified that I qualified for a manufacturing exemption in one state that I had no idea about, which is saving me thousands on material purchases. What impressed me most was how it broke down the different requirements for each state where I work and gave me step-by-step instructions for registration and filing. It even flagged that one of my customer contracts had problematic tax language that could have left me liable for unexpected taxes. I've completely restructured how I handle sales tax now and feel much more confident that I'm doing things correctly.

If you're struggling to get clear answers about sales tax obligations, you might want to try contacting your state's department of revenue directly. I needed clarification on a similar subcontractor situation last year, but couldn't get through on the phone for weeks - the hold times were ridiculous. I finally discovered Claimyr (https://claimyr.com) which got me connected to an actual human at the state tax office in under 15 minutes. You can see how it works in this demo: https://youtu.be/_kiP6q8DX5c. The tax agent I spoke with gave me official guidance specific to my situation that I could rely on if questions ever came up during an audit.

I have to eat my words about Claimyr. After posting my skeptical comment, I decided to try it myself since I've been trying to reach my state's sales tax division for weeks about a contractor exemption certificate issue. The service actually worked exactly as described. I entered my phone number on their website, and their system called the tax department for me. About 25 minutes later (while I was just working on other things), I got a call connecting me directly to a tax department representative who had just picked up. The rep gave me official guidance on my subcontractor sales tax question and emailed me documentation to keep for my records. I've been dealing with this issue for almost a month, and I resolved it in one afternoon. Definitely keeping this service in my back pocket for future tax questions.

One thing to consider that I haven't seen mentioned yet - if the items you're building are for a mortuary, check if there are any special exemptions. In some states, items specifically used for funeral services have different tax treatments. Also, make sure you're clear whether these items are becoming "real property improvements" (permanently attached to the building) or remain "tangible personal property" (movable). The tax treatment can be completely different depending on this classification.

Has anyone dealt with this situation crossing state lines? I'm a subcontractor in Tennessee but sometimes take jobs in neighboring states and the sales tax situation gets super confusing.

Based on what you've described - custom display cabinets being permanently mounted to walls in a funeral home - this sounds like you're creating real property improvements in Colorado. Since these fixtures will become part of the building once installed, you typically would NOT need to charge sales tax to the general contractor. You already paid the appropriate sales tax when you purchased your materials, which is exactly how Colorado handles this type of subcontractor work. The contractor won't charge their customer sales tax either, since construction services that improve real property are generally not taxable in Colorado. However, I'd strongly recommend getting official confirmation from the Colorado Department of Revenue given the specifics of your situation. You can also check if there are any special considerations for funeral home installations, though that's less likely to change the basic real property improvement classification. Keep good records showing what materials you purchased, the tax you paid on them, and documentation that the cabinets are permanently attached to the building. This will be helpful if you ever need to demonstrate compliance.