Plumbing contractors carry some of the highest deductible expenses of any trade — work trucks, specialized equipment, materials, licensing, and labor — but most are capturing only a fraction of what they're legally owed. The tax code rewards trades businesses that document well.
We've worked with plumbing contractors across North Carolina and the pattern is consistent: significant overpayment, and a short list of missed deductions causing all of it. Here are the 10 that move the needle most.
Your full-size work truck or van — including purchase price, insurance, fuel, oil changes, tires, repairs, and registration — is deductible based on business use percentage. For trucks used more than 80% for business, the actual expense method almost always beats the standard mileage rate.
Log every mile: service calls, supply pickups, inspection sites, and trips to the supply house. The 2026 IRS standard mileage rate is 70¢/mile — but actual expenses typically produce a larger deduction for heavy commercial vehicles.
A new work truck purchased and placed in service in 2026 can be fully deducted in the year of purchase using Section 179, rather than depreciated over 5 years. This can create a five-figure deduction in year one.
Pipe wrenches, drain snakes, hydro-jetting equipment, camera inspection systems, pipe cutters, soldering equipment, pipe threaders, and every other tool used on the job. High-cost items include hydro-jet machines ($3,000–$15,000), sewer camera systems ($2,000–$8,000), and pipe fusion equipment.
Apply Section 179 to deduct all qualifying equipment 100% in the year of purchase. For smaller purchases under $2,500, the de minimis safe harbor election allows immediate expensing without tracking depreciation schedules.
Copper, PVC, CPVC, PEX, and ABS pipe; fittings, valves, fixtures, water heaters, toilets, sinks — all materials purchased for jobs are deductible as cost of goods or direct job costs. Don't overlook consumables: Teflon tape, flux, solder, and pipe cement add up fast across hundreds of service calls.
Track material cost per job so you know your true gross profit per service type. Contractors who don't job-cost consistently understate deductions and underprice their work — a double hit to profitability.
NC State Board of Examiners of Plumbing, Heating & Fire Sprinkler Contractors license fees are 100% deductible. Continuing education required to maintain licensure — including code update courses, backflow prevention certifications, and gas piping certifications — is fully deductible as an ordinary business expense.
Association dues for PHCC (Plumbing-Heating-Cooling Contractors), ASPE (American Society of Plumbing Engineers), and any local trade chapters are also deductible in full.
General liability insurance, commercial auto, workers' compensation, and umbrella coverage are all fully deductible as ordinary business expenses. Required license bonds — which the NC licensing board mandates for plumbing contractors — are also 100% deductible.
Insurance premiums are often paid annually and easy to miss when doing quarterly bookkeeping. A clean chart of accounts catches every premium in the right period.
Apprentice plumbers classified as employees: their wages plus the employer's share of FICA are fully deductible. Specialty subcontractors — gas fitters, HVAC crossovers, drain tile contractors — are deductible when engaged for specific jobs.
Issue W-2s for employees and 1099-NEC forms for subcontractors paid $600 or more. Misclassifying employees as independent contractors is one of the most common audit triggers for contractors. Get this right from the start.
If you use a dedicated space at home for dispatching calls, invoicing, customer follow-up, permit research, or code lookups — that space qualifies for the home office deduction. The space must be used regularly and exclusively for business.
Simplified method: $5 per square foot, up to 300 square feet ($1,500 maximum). The regular method uses the actual percentage of your home used for business, applied to mortgage interest or rent, utilities, and insurance — often producing a larger deduction.
Business cell phone usage (based on business-use percentage), service dispatch software subscriptions (ServiceTitan, Jobber, mHelpDesk), estimating and material pricing apps, and GPS fleet tracking subscriptions are all deductible. If you use your phone 80% for business, 80% of the bill is a write-off.
Accounting software, invoicing platforms, and any SaaS tool used to manage the business side qualify as ordinary business expenses. Track these as recurring software costs, not miscellaneous expenses.
Branded uniforms with the company logo are deductible — they're not suitable for everyday wear, which satisfies IRS requirements. Personal protective equipment (PPE) including knee pads, safety glasses, cut-resistant gloves, and steel-toed boots is fully deductible. Hazmat and sewer-rated gear for drain and sewer work qualifies as well.
Generic work clothes — jeans, plain t-shirts — are generally not deductible. Logoed uniforms and specialized safety gear are. Keep purchase receipts and note the business purpose.
If your plumbing business nets $80,000 or more per year and you're operating as a sole proprietor or single-member LLC, you're paying 15.3% self-employment tax on every dollar of profit. That's $12,240 in SE tax on $80K net — before federal and state income tax.
By electing S-Corporation status, you split income between a reasonable salary (subject to payroll tax) and an owner distribution (not subject to SE tax). At $140,000 net with a $70,000 salary, this structure saves approximately $10,710 per year from this change alone.
Learn more: Should You Elect S-Corp Status?
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