Warranty work costs real money, but most plumbing businesses never see the true number because the labor hides in general payroll and the materials hide in general supply costs. The fix is straightforward. Give warranty expenses their own home in your chart of accounts and track every callback against the original job.

Start by creating a Warranty Expense account in your books. Under that, you may want sub-accounts for warranty labor and warranty materials so you can see what’s driving the cost. When a technician goes back to redo or fix work, that time entry and any parts used should hit the warranty account rather than getting lumped in with regular job costs. If the callback hours sit in general payroll, you’ll never know how much warranty work is actually costing you each month.

The more valuable step is linking each callback to the original job. This is where job costing pays off. When you tie warranty work back to the first job, you can track the true profitability of that job after accounting for the callback. Over time, this data reveals patterns you can act on. Maybe a specific brand of part keeps failing. Maybe certain job types have a higher callback rate. Maybe one technician generates more warranty visits than others. You can’t fix what you can’t see, and generic expense categories won’t show you any of this.

Many plumbers also set up a warranty reserve by setting aside 1 to 3 percent of revenue to cover future warranty costs. This is a planning tool more than a strict accounting requirement, but it gives you a realistic picture of profitability. If you’re bidding jobs without accounting for the likelihood that some percentage will need a return visit, your margins are thinner than you think.

When you record a callback, note the original job number, the technician who did the initial work, the reason for the callback, and what was done to resolve it. This doesn’t have to be complicated. A simple notes field or memo on each warranty transaction is enough. The goal is building a dataset you can review quarterly to spot trends and make better decisions about training, materials, and pricing.

Don’t forget that warranty labor is a real cost even if no new invoice goes out. Your technician is on the clock, your truck is burning fuel, and you’re using parts. All of that should be captured. If you’re running small business bookkeeping without separating warranty costs, you’re overstating your profit on completed jobs and understating the drag that callbacks create.

Getting this right doesn’t require a complicated system. It requires discipline about categorizing warranty transactions separately and consistently tying them back to the original job. Once that habit is in place, you’ll have clear numbers to work with instead of a vague sense that callbacks are eating into your bottom line.