Bookkeeping 101 for Plumbers, Electricians, and Contractors
If you're a plumber, electrician, or contractor, you didn't get into this business because you love spreadsheets. You got into it because you're good at the work — diagnosing a busted pipe, wiring a panel, framing out a new build. The business side, and especially the bookkeeping side, was probably never part of the plan.
But here's the truth I've seen over and over again working with trade businesses here in Jacksonville, FL: the contractors who build lasting, profitable companies are the ones who eventually get serious about their numbers. You don't have to become an accountant. You just have to understand the basics — and know when to ask for help.
This is that guide.
Why Bookkeeping Hits Differently for Trade Businesses
Service businesses in general have unique bookkeeping challenges, but trades have some specific wrinkles that make it even more important to stay organized.
Think about it: you might have five jobs running at the same time across different parts of Jacksonville. Each one has different materials, different labor hours, different timelines, and different profit potential. Without proper tracking, you have no idea which jobs are actually making you money and which ones are quietly draining it.
Add in the seasonal cash flow swings, unpredictable material costs, subcontractors, equipment, and a truck (or three), and you've got a financial picture that's genuinely complicated. That's not a problem — that's just the reality of running a trade business. The answer is solid bookkeeping practices.
The Foundation: Separate Business and Personal Finances
I'm going to start here because this is the number one issue I see when I start working with contractors. Personal and business expenses all mixed together in one bank account.
I understand how it happens. When you're first starting out, it feels easier to just use your personal account. Then a few years go by and suddenly you're trying to figure out your taxes and you've got Home Depot receipts next to your kid's soccer camp charges and nobody — not even you — can make sense of it.
Here's what you need to set up if you haven't already:
A dedicated business checking account. Every dollar your business earns goes in here. Every business expense comes out of here.
A business credit card. Great for tracking expenses and building business credit. Pay it off monthly.
Separate savings for taxes. I recommend setting aside 25–30% of your net income in a separate account. When quarterly estimated taxes come due, you'll be glad it's there.
This single step — separating finances — makes every other part of bookkeeping dramatically easier.
Tracking Income: Know What's Coming In
For most contractors, income comes in a few different forms: deposits, progress payments, final invoices, and sometimes retainage. Each of these needs to be recorded when it hits your account.
In QuickBooks, you can set up your income accounts to reflect the type of work you do. For example, you might separate:
Residential service calls
Residential installation
Commercial projects
Service agreements or maintenance contracts
Why does this matter? Because at the end of the month — or the end of the year — you want to know which part of your business is actually driving revenue. A lot of contractors are surprised when they break it down and realize that their high-volume residential service calls generate less revenue than their fewer-but-larger commercial contracts.
Also important: don't record income until you've actually received the money. This is called cash basis accounting, and it's what most small contractors use. Record the invoice when it goes out, but track when it's actually paid.
Tracking Expenses: Where the Money Goes
This is where trade businesses tend to have the most categories and the most complexity. Let me break down the main expense buckets you need to be tracking:
Materials and Supplies
Every piece of PVC pipe, every electrical component, every bag of concrete. These are direct job costs. If you're buying materials for a specific job, that cost needs to be attached to that job.
Labor
Whether you have employees on payroll or you're using subcontractors (or both), labor is usually your biggest expense. Track it carefully. For employees, your payroll records will tie directly to your bookkeeping. For subs, keep your 1099s organized — QuickBooks can help you manage this.
Vehicle and Truck Expenses
Your truck is a business tool. Fuel, insurance, repairs, oil changes, registration — all deductible. You have two options with the IRS: track actual expenses, or use the standard mileage rate (67 cents per mile as of 2024). Either way, you need a mileage log. There are simple apps that make this easy.
Tools and Equipment
Hand tools, power tools, specialty equipment. Small tools under $2,500 are generally expensed immediately. Larger equipment may need to be depreciated over time. This is an area where a bookkeeper or CPA can help you maximize your deductions legally.
Insurance
General liability, workers' comp, vehicle insurance for your fleet. All deductible.
Uniforms and Work Clothing
If it's safety gear or clothing required for your trade (work boots, hard hats, high-vis vests), it's deductible.
Software and Technology
QuickBooks, scheduling software, your CRM, GPS fleet tracking — these are business expenses.
Home Office
If you run your business from home and have a dedicated workspace, a portion of your home expenses may be deductible. This one has specific IRS rules, so get guidance before you take it.
Job Costing: The Most Powerful Tool You're Probably Not Using
Here's where bookkeeping goes from "keeping the IRS happy" to "actually building a better business."
Job costing means tracking income and expenses for each individual job. When you know what a job actually cost you versus what you billed, you know your real profit margin on that job.
Let me give you an example. Say you're an HVAC contractor and you do a system replacement — you bill the customer $8,500. Materials were $3,200. Labor (your time and one tech) was $1,400. Truck time and fuel, $120. Permits, $75. Total costs: $4,795. Your profit on that job: $3,705, or about a 44% margin. That's solid.
Now compare that to a service call you did the same week. You billed $285. Parts were $40. But it took your tech two hours at $35/hour, plus drive time — let's call it three total hours. That's $105 in labor. Fuel: $20. Total costs: $165. Profit: $120, or 42%. Also solid, and faster.
Now imagine you didn't track any of this. You just looked at your bank account at the end of the month and thought "yeah, seems okay." You'd never know that your commercial maintenance contracts are only hitting 28% margins because you keep underestimating labor hours when you bid them.
That's the power of job costing. In QuickBooks, you can set up customers and jobs, assign all income and expenses to each job, and run a job profitability report. It takes discipline to do consistently, but it is one of the most valuable things a trade business can do.
Understanding Your Profit Margins
Let's talk about the numbers every contractor should know:
Gross Profit Margin = (Revenue – Direct Job Costs) ÷ Revenue × 100
Direct job costs are materials, labor, subs, and other costs tied directly to doing the work. For most trade businesses, healthy gross margins run between 40% and 60%, depending on the type of work and your market.
Net Profit Margin = (Revenue – All Expenses) ÷ Revenue × 100
This is what's left after you subtract overhead — rent, insurance, office expenses, software, marketing. A healthy net margin for a trade business is typically 10–20%.
If your gross margins look good but your net margins are thin, that tells you overhead is eating your profits. If both are low, you may have a pricing problem or a labor efficiency problem.
You can't fix what you can't see. Bookkeeping gives you the visibility to make better business decisions.
The Biggest Mistakes I See Contractors Make
After working with trade businesses in the Jacksonville area, here are the patterns I see most often:
1. Mixing personal and business money. Already covered this one. It creates a mess that costs real time and money to untangle.
2. Paying subs in cash without records. If you pay a subcontractor $600 or more in a year, you need to file a 1099. If you're paying cash without records, you may not be able to deduct that expense — and you're opening yourself up to IRS scrutiny.
3. Not tracking mileage. This is free money. At 67 cents per mile, driving 15,000 business miles a year is a $10,050 deduction. Not tracking it means leaving that on the table.
4. Waiting until tax time to organize the year. By then it's too late to make strategic decisions. It's also expensive — CPAs charge more for cleanup work than for clean records.
5. Not invoicing promptly. Cash flow is everything in a trade business. The faster you invoice, the faster you get paid. QuickBooks makes it easy to invoice on-site from your phone the moment you finish a job.
When to Bring in Professional Help
DIY bookkeeping works fine when your business is simple. But here are some signs it's time to bring in a professional bookkeeper:
You're spending more than a few hours per week on the books
You have employees or multiple subcontractors
You're doing job costing and it's getting complicated
You keep running out of cash even when business seems good
Tax season consistently brings surprises
You want to apply for a business loan and need clean financials
As a certified QuickBooks ProAdvisor based here in Jacksonville, I work specifically with trade businesses — HVAC companies, plumbers, electricians, contractors, and more. I understand the specific expenses, the job costing needs, and the cash flow patterns that come with your industry. My job is to keep your books accurate, give you clear numbers every month, and make sure nothing falls through the cracks.
You built this business with your hands and your expertise. Let me handle the numbers so you can focus on the work.
Ready to get your books working for your business? Schedule a free 15-minute consultation at maurice-davis.com.
