Your QuickBooks dashboard says you made $180,000 last year. Your bank account tells a different story. If that gap sounds familiar, the problem probably isn’t your bookkeeping habits — it’s that QuickBooks wasn’t built for construction out of the box, and nobody ever set it up for how contractors actually work.

We look at contractor books every week, and the same mistakes show up again and again — sometimes all in the same file. None of them are catastrophic on its own. Together, they’re why so many contractors feel like their books and their bank accounts are telling two different stories.

What are the most common QuickBooks mistakes contractors make?

The six QuickBooks mistakes we see most often in contractor books: not job-costing by project, using a generic chart of accounts, miscoding subcontractor payments, letting retainage disappear into regular accounts receivable, skipping monthly reconciliation, mixing job costs with overhead, and running cash-basis reports when the business actually needs job-costed numbers. Every one of them is fixable in an afternoon once you know what to look for.

Mistake 1: You’re not job-costing by project

Here’s what we see most: every job gets dumped into one general “Income” and one general “Job Materials” account. QuickBooks can tell you the company made money this year. It can’t tell you whether the Wilson kitchen remodel made money, or whether it quietly lost $4,000 while the Grafton deck job carried the whole month.

The fix: turn on QuickBooks’ Projects feature (or Jobs, in older versions) and assign every invoice, bill, and timesheet entry to a specific job. Ten minutes of setup per project. It’s the single highest-leverage change a contractor can make in
QuickBooks

Mistake 2: Subcontractor payments are miscoded

We regularly find subcontractor payments coded as “Contract Labor,” “Outside Services,” and “Materials” — all in the same file, sometimes for the same subcontractor. Beyond making job costing impossible, it puts your 1099-NEC filing at risk. The IRS expects consistent, traceable records of what you paid each contractor and for what.

The fix: create one dedicated Subcontractor Labor account under COGS, code every payment to that vendor there, and make sure each subcontractor has a completed W-9 on file before the first payment goes out.

Mistake 3: Retainage disappears into regular accounts receivable

If you’re a commercial contractor, you’re probably holding back retainage on subs and having it held back on you. Most QuickBooks files just leave retainage sitting in the same A/R bucket as everything else. This means your aging reports are wrong, and it’s easy to forget retainage is owed until months later.

The fix: set up a separate “Retainage Receivable” and “Retainage Payable” account. It takes retainage out of your regular A/R aging and puts it somewhere you’ll actually track it until its release.

Mistake 4: Bank and credit card accounts aren’t reconciled monthly

“Close enough” is the phrase we hear most. Transactions get imported and auto-categorized by QuickBooks’ bank feed, nobody checks them against the actual statement, and errors compound month over month. A duplicated deposit or a miscategorized fuel purchase in March is still wrong in December if nobody reconciled in between.

The fix: reconcile every bank and credit card account to the statement every single month — not just at tax time. It’s the fastest way to catch errors while they’re still a five-minute fix instead of a five-hour one.

Mistake 5: Job costs and overhead are mixed together

This is Mistake 1 and Mistake 2’s close cousin: even contractors who job-cost sometimes let overhead — office rent, the bookkeeper’s own time, insurance, admin payroll — bleed into job cost accounts. That makes every project look less profitable than it actually is, and it makes it impossible to know your true overhead rate for bidding future jobs.

The fix: keep overhead in its own section of the chart of accounts, separate from COGS/job costs entirely. Then calculate an overhead rate periodically and build it into your bids — instead of guessing.

Mistake 6: You’re looking at cash-basis reports when you need job-costed, accrual data

None of these six fixes require new software or a full rebuild. They require about half a day: turn on Projects, rebuild the chart of accounts for construction, create a dedicated subcontractor account, separate retainage, reconcile monthly going forward, split overhead from job costs, and check whether your reports are running cash or accrual.

If you want a head start, our free guide walks through the QuickBooks setup we use with contractor clients, step by step.

Bottom Line

Six fixes, about half a day of setup, and QuickBooks starts telling you the truth about which jobs make money. If your numbers and your bank account have been disagreeing, this is almost always why.

FAQ

Frank Fiore, CPA, is the President of Accounting Freedom, based in Mundelein, Illinois and Grafton, Wisconsin. For more than 20 years he’s helped contractors and small business owners across Illinois and Wisconsin get straight answers about their books — no jargon, no upsell. Frank is also the founder of Payroll Freedom, the firm’s sister brand for payroll services.

This article is provided for general informational purposes only and does not constitute tax, legal, accounting, or financial advice. Every business situation is different. Before acting on anything you read here, please consult with a qualified advisor — including, we hope, us. Reach out to Accounting Freedom for guidance specific to your situation.