Tools and small equipment are the most consistent deduction for plumbers. Wrenches, augers, torches, fittings, testing equipment, anything you buy to do the work. Items under roughly $2,500 per invoice can usually be expensed the year you buy them under the de minimis safe harbor. Keep receipts and code these to a tools or small equipment account in your books as you go.

Vehicle expenses are often the largest deduction but also the most commonly messed up. You have two options. Standard mileage at the IRS rate (67 cents per mile for 2024) requires a mileage log showing date, destination, purpose, and miles. Actual expenses means deducting gas, insurance, repairs, registration, depreciation, and lease payments, multiplied by your business use percentage. You can’t switch from actual to standard later if you claim depreciation upfront, so pick carefully. For a work truck driven almost exclusively for service calls, actual expenses often wins. Either way, track mileage with an app like MileIQ because recreating a log at year end doesn’t hold up.

Licensing and insurance are fully deductible. California contractor license fees, bond premiums, general liability, commercial auto, workers comp, and any professional association dues all qualify. Same for continuing education required to maintain your license or learn new skills like backflow certification.

Uniforms and safety gear count when they’re not suitable for everyday wear. Branded shirts, steel-toe boots, gloves, knee pads, safety glasses, respirators, and hard hats are deductible. A plain pair of jeans you also wear to dinner is not. Laundry and cleaning costs for qualifying work clothing are also deductible.

Section 179 and bonus depreciation let you immediately expense larger equipment purchases that would otherwise depreciate over five to seven years. Drain cameras, jetters, pipe threaders, trailers, and even vehicles over 6,000 pounds GVW often qualify. California partially conforms to Section 179 but caps the state deduction lower than federal, so your California return will differ from your federal. A bookkeeper who works with skilled trades can make sure the federal and state books handle these differences correctly.

Your cell phone is deductible for the business-use percentage. If 80% of your calls are customers, suppliers, and dispatch, deduct 80% of the bill. Same logic for internet if you run the business from home.

Home office deduction applies if you have space used regularly and exclusively for business, even if the physical work happens on job sites. Admin work, scheduling, invoicing, and ordering parts all count. The simplified method gives you $5 per square foot up to 300 square feet. The actual method uses a percentage of home expenses based on square footage. The home office also unlocks mileage from your home to the first job of the day, which is otherwise non-deductible commuting.

Other commonly missed deductions include marketing costs, job site parking and tolls, permit fees, subcontractor payments (with 1099s filed where required), accounting and legal fees, business bank and credit card fees, and software subscriptions for scheduling, invoicing, or bookkeeping.

The deductions themselves aren’t complicated. What trips plumbers up is documentation. No receipts means no deduction if you’re audited, and the Franchise Tax Board audits California small businesses more aggressively than most states. Get a system in place to capture receipts as they happen, separate business purchases from personal ones, and reconcile monthly so nothing slips through. The Pasadena bookkeepers at A Squared help skilled trades operators set up systems that make tax time straightforward instead of a scramble through a shoebox of fading receipts.