Job Costing Basics: Are You Actually Making Money on Each Job?
Job costing is the practice of tracking all revenue and all costs for each individual project separately. Labor, materials, subcontractors, equipment rental, permits, dump fees — every dollar in and every dollar out, attached to the specific job it belongs to.
Without job costing, you know whether the business is profitable in aggregate. You do not know which jobs are making money and which are eating it. A contractor who finishes ten jobs in a month and nets $8,000 might have made $20,000 on four jobs and lost $12,000 on six — and has no idea which projects were the winners.
The practical setup: assign a job number or code to every project before work begins. Every expense — lumber from Home Depot, hours from a helper, equipment rental — gets coded to that job at the time it is incurred. When the job closes, you run a job cost report that shows revenue minus all direct costs. That number is your gross profit on that project.
Do this consistently and two things happen. First, you know your actual margin by job type. Renovation work makes more than new construction? Kitchen remodels are better than bathrooms? The data will tell you. Second, your estimates improve because they are built on actual historical cost data rather than gut feel. Contractors who track job costs systematically outbid and outperform those who do not — not because they work harder, but because they know what things actually cost. For context on common mistakes that hurt profitability, see our post on bookkeeping mistakes Inland Empire contractors make.
Mileage and Equipment Deductions: Take What You’re Owed
Contractors drive constantly — to job sites, to suppliers, to client walkthroughs. Every business mile is a deduction, and at the 2024 IRS standard rate of 67 cents per mile, those deductions add up fast. A contractor who drives 15,000 business miles in a year has a $10,050 deduction they can claim without spending a dollar on anything.
The catch: you need a mileage log. The IRS requires documentation of the date, destination, purpose, and miles for each business trip. Apps like MileIQ or TripLog make this close to automatic — they track trips via GPS and let you swipe to classify them as business or personal. If you are not using one, start today. The IRS does not accept estimates or reconstructed logs prepared at tax time.
For equipment, Section 179 is the most powerful deduction available to most contractors. It allows you to deduct the full purchase price of qualifying equipment — tools, trailers, work trucks, machinery — in the year of purchase rather than depreciating it over five to seven years. A $25,000 work truck purchased and put into service before December 31 can reduce your taxable income by $25,000 in the same year. There are limits and conditions (vehicle must be used more than 50% for business, there are annual deduction caps), but for most contractors buying working equipment, Section 179 is worth understanding before year-end. See our guide on small business tax deductions for the full breakdown.
Tools and materials below a certain value can often be expensed directly rather than depreciated. The IRS has a $2,500 safe harbor for tangible property — items under that threshold can be deducted in the year of purchase without a formal depreciation schedule. For a contractor buying hand tools, power tools, and smaller equipment throughout the year, this adds up.
1099 vs. W-2: What Your Classification Actually Means
If you work as an independent contractor — a subcontractor on a larger job, a 1099 trade worker, a gig-economy service provider — your tax situation is fundamentally different from an employee’s. No employer is withholding taxes from your payments. No employer is paying half your Social Security and Medicare taxes. You owe all of it, and you owe it quarterly.
As a 1099 worker, you pay self-employment tax (15.3% on net self-employment income up to the Social Security wage base, 2.9% above it) in addition to federal and California income tax. On $80,000 of net contractor income, self-employment tax alone is roughly $11,300. Add federal income tax at 22% and California income tax at 9.3%, and the effective tax burden on that income is around 40–45% depending on deductions.
This is not a surprise if you plan for it. It is a disaster if you do not. The most common cash crisis for first-year contractors: receive payments all year, spend freely, pay a massive tax bill in April, and find the account empty. The fix is simple — set aside 25–30% of every payment received into a dedicated savings account earmarked for taxes. Do not touch it. Pay quarterly estimates from it on schedule.
If you are a general contractor who hires subcontractors, you have 1099 obligations of your own. Any sub paid $600 or more during the calendar year requires a 1099-NEC filed by January 31 of the following year. That means collecting W-9 forms before you issue the first check — not at year-end when you are chasing people who have moved on. Set up the paperwork before the work starts.
Quarterly Estimated Tax Payments: The Calendar That Matters
The IRS runs on a pay-as-you-go system. Employees satisfy this via payroll withholding. Contractors satisfy it via quarterly estimated tax payments. If you expect to owe more than $1,000 in federal taxes for the year, the IRS requires you to make four estimated payments on this schedule:
- Q1: April 15 (covers January–March income)
- Q2: June 15 (covers April–May income)
- Q3: September 15 (covers June–August income)
- Q4: January 15 (covers September–December income)
California requires the same for taxpayers who expect to owe $500 or more to the FTB, with similar due dates. Missing or underpaying these installments results in an underpayment penalty assessed automatically — even if you pay the full amount owed by April 15. The penalty is not huge, but it is avoidable.
The safest approach: each quarter, total your net income for the period, apply the combined tax rate, and pay that amount. A bookkeeper who is reconciling your books monthly can generate this number in minutes — you write the check, file the payment electronically through IRS Direct Pay, and move on. No surprises in April. For how good financial records feed directly into loan applications and credit access, see our post on how clean books help you get a business loan.
Receipt Tracking for Materials: Deductions You Cannot Claim Without Documentation
Materials are often a contractor’s largest expense category — lumber, pipe, wire, tile, concrete, hardware. Every dollar of materials purchased for a job is a deductible business expense. But the IRS requires substantiation: receipts, invoices, credit card statements showing the purchase, the amount, and the business purpose.
The practical problem: contractors buy materials constantly, often in cash, from multiple suppliers, across multiple jobs. Without a system, those receipts get lost in a truck cab, a pocket, a glove box. By tax time, thousands of dollars of legitimate deductions have no documentation and cannot be claimed.
The fix is a habit, not software. Photograph every receipt the day you get it. Apps like Dext (formerly Receipt Bank), QuickBooks Receipt Capture, or even a dedicated email address where you forward photos work fine. The critical thing is immediacy — the photo gets taken before the receipt disappears. Then code the expense to the correct job at the same time. One step, one habit, done.
For larger material purchases on accounts at suppliers like Home Depot Pro, Fastenal, or Ferguson, request monthly statements and reconcile them to your bank or credit card. Supplier accounts often have better records than paper receipts — leverage them.
Separating Personal and Business Expenses: Non-Negotiable
This is the most basic rule in small business bookkeeping and the most commonly violated among contractors: never run personal expenses through your business account, and never pay business expenses from personal accounts.
The practical problems with commingling: your P&L is wrong because personal expenses inflate your costs. Tax preparation is a mess because every transaction requires categorization. If you are ever audited, the IRS will scrutinize a commingled account heavily — and disallow any deductions they cannot clearly attribute to business use. Banks and lenders will not extend credit to a business with mixed accounts because they cannot assess the actual financials. See our post on 5 signs you need a bookkeeper — commingled accounts is number one on the list.
The fix: open a separate business checking account and a business credit card if you do not have them. Use the business account exclusively for business income and expenses. Use the personal account exclusively for personal spending. If you take money out of the business for personal use, do it as a single owner’s draw transfer — one clean transaction per transfer, clearly labeled.
For sole proprietors and single-member LLCs, this is a discipline question, not a legal requirement. For S-corps and multi-member LLCs, it is a legal and tax obligation. Either way, the cost of separation is zero. The cost of not separating is paid at tax time and during every conversation with a lender.
What Contractor Books Look Like When They’re Working
A contractor with solid bookkeeping can answer these questions at any point in the year: Which jobs made money this month? What is my effective tax rate on what I have earned? Am I on track with quarterly estimates? What is my cash position after setting aside for taxes and materials on open jobs?
That is not complexity — it is discipline. Monthly reconciliation, job costing on every project, a mileage log, receipts captured same-day, and personal expenses cleanly separated. A bookkeeper handles the reconciliation and reporting; you provide the raw data as the work happens.
Ledger Bee LLC works with independent contractors and subcontractors throughout Southern California — construction trades, service businesses, gig-economy operators. Whether you are a GC in the Inland Empire, a plumber in San Diego, or a 1099 electrician in Los Angeles, the financial fundamentals are the same. We bring clarity to the numbers so you can focus on the work.