The biggest challenge for plumbers is that you’re often running multiple jobs in a single day. A construction company might spend weeks on one project, but a plumber could hit three service calls before lunch and start a repipe after. That pace makes it easy to let expense tracking slip. The fix is building a simple system and sticking to it daily.

Start by setting up projects or jobs in QuickBooks Online. Every active job gets its own project. When you buy materials, enter a bill, or log labor hours, you assign that cost to the specific job. This is how you stop guessing which jobs made money and start seeing actual numbers.

Materials are usually your most trackable cost. If you have a supply house account with Ferguson or a local distributor, ask them to add a job reference or PO number to each order. Most supply houses will do this. When the monthly statement arrives, every line item already points to the right job. For cash purchases at Home Depot or Lowe’s, snap a photo of the receipt and note the job name before you leave the parking lot. Waiting until Friday to sort through a pile of receipts means you’ll misallocate or miss something.

Labor is where most plumbing businesses lose visibility. If you have employees, they need to track their hours by job every day. Even a simple timesheet that lists “8am-11am, Johnson water heater” and “12pm-4pm, Elm Street repipe” gives you what you need to allocate labor costs. Apps like Busybusy or even basic time tracking in QuickBooks work fine as long as the crew actually uses them. Your own hours count too, especially if you want to understand true job profitability.

Subcontractor costs are straightforward. When you bring in someone for trenching, concrete, or specialized work, code their invoice to the job they worked on. Don’t let sub invoices sit in a general expense category.

Vehicle and fuel costs are trickier. Some plumbers allocate a per-mile cost to each job based on distance driven. Others treat vehicle expenses as overhead and spread them across all jobs proportionally. Either method works, but pick one and be consistent. The important thing is not to ignore these costs entirely since your trucks are a real expense of doing business.

For larger projects like whole-house repipes, bathroom roughins, or commercial work, track expenses in more detail. Break the job into materials, labor, subcontractors, and permits. Compare actual costs against your estimate when the job is done. This comparison is where you learn whether your pricing is right or whether you’re consistently underquoting certain types of work.

The discipline of coding every expense to a job pays off at two points. First, during the job, when you can see if costs are running over your estimate. Second, after a month or quarter of completed jobs, when you can look at profitability by job type and figure out which work earns the best margins. Many plumbers discover that their most requested services are actually their least profitable once all costs are accounted for.

If you’re behind on organizing your books or have never tracked by job before, skilled trades bookkeeping requires someone who understands how field service businesses actually operate. A generic approach won’t capture the nuances of supply house accounts, job-level time tracking, and material markups.

The system doesn’t have to be complex. One business bank account, one business card, digital receipts, time logged by job daily, and weekly reconciliation. That’s the foundation. Once those habits are in place, your bookkeeping services produce reports that actually tell you something useful instead of just satisfying your accountant at tax time.