Contractors don’t just sell a product or bill hourly for services. Every project is its own profit center with unique costs, timelines, and variables. Generic bookkeeping treats all revenue and expenses as one pool, which tells you almost nothing about whether individual jobs are making or losing money.

The biggest difference is job costing. A contractor needs to track labor, materials, and subcontractor costs against each specific project. When your bookkeeper lumps all material purchases into one “materials” account and all sub payments into one “subcontractor” account, you can see company-wide totals but you have no idea if the Smith remodel made $15,000 or lost $3,000. That project-level visibility is what separates useful books from useless ones.

Progress billing and retainage create another layer of complexity that most industries don’t deal with. Contractors often bill based on percentage of completion or milestones, and customers frequently hold back 5% to 10% as retainage until the job is finished. A bookkeeper unfamiliar with construction might record a progress bill as full revenue or ignore retainage entirely. Both distort your actual financial position and can make you think you have more cash coming in than you actually do.

Cash flow in construction is notoriously uneven. You’re buying materials and paying subs weeks or months before you collect final payment. A specialized bookkeeper understands this cycle and can help you see where cash gaps are forming before they become emergencies. This is especially true in the Phoenix market where contractors often juggle multiple residential and commercial projects at once across different stages.

Then there’s subcontractor management. Contractors work with dozens of subs over the course of a year, and every one paid $600 or more needs a 1099 at year end. Tracking sub payments by vendor and collecting W-9s throughout the year is something a construction-savvy bookkeeper handles as part of the normal workflow rather than treating it as a January scramble.

WIP reporting matters too. You need to know the status of every active project at any given time: what’s been billed, what’s been spent, what’s committed but not yet invoiced, and what’s left in the budget. Without WIP tracking, you’re guessing at your overall financial health based on your bank balance. That works fine until it doesn’t, usually right when you need to cover payroll or a material deposit on a new job.

A general bookkeeper can categorize transactions and reconcile bank accounts accurately. But they won’t know that a $40,000 lumber delivery needs to be coded to a specific job and phase, that the $8,000 retainage on your last invoice isn’t lost revenue, or that your P&L means nothing without job-level detail underneath it. Working with a small business accounting firm that understands construction means your books actually reflect how your business operates, and you get numbers you can use to bid better, manage cash, and know your real margins on every project.