The most important thing for HVAC and plumbing companies is separating service work from installation work in your books. These are essentially two different businesses running under one roof. Service calls carry higher margins but lower revenue per ticket. Installations bring in more per job but come with significant material costs and sometimes subcontractor expenses. If everything gets lumped into one revenue line, you have no idea which side of the business is actually profitable.

Set up your chart of accounts to track revenue and cost of goods sold separately for service, maintenance agreements, and installations. This gives you gross profit by revenue stream instead of one blended number. When you can see that your service department runs at 55% gross margin but installations come in at 28%, you make better decisions about pricing, hiring, and where to invest in growth. Most skilled trades companies that struggle financially have this problem. Their books don’t reflect how the business actually operates.

Track job costs on any installation or project over a certain dollar amount. Every material purchase, labor hour, and permit fee should be coded to the specific job. When a technician pulls a water heater from truck stock for an install, that unit needs to hit the job’s costs rather than a general materials expense. This doesn’t need to be complicated, but it does need to happen consistently.

Parts inventory is a common pain point. Most HVAC and plumbing companies keep truck stock and warehouse inventory. You don’t need to count every fitting and coupling, but you should track high-value items like equipment units, water heaters, and compressors. A periodic inventory count reconciled against your books prevents shrinkage from quietly eating your margins.

Payroll in the trades gets complicated fast. You may have technicians earning hourly rates with overtime, on-call pay, spiffs or commissions on maintenance agreement sales, and different rates for service versus install work. Your bookkeeping needs to handle these variations accurately because payroll is typically the largest single expense for an HVAC or plumbing company.

Seasonal cash flow hits HVAC companies especially hard. Summer and winter are peak seasons while spring and fall can slow down significantly. Your bookkeeping should include cash flow awareness so you can build reserves during busy months to cover the slower periods. Maintenance agreement revenue helps smooth out the peaks and valleys, and that’s another good reason to track it as its own revenue stream.

Vehicle and fleet expenses deserve their own attention too. Fuel, maintenance, insurance, and depreciation on service trucks add up. Knowing your cost per truck per month helps you decide about fleet size and when to replace aging vehicles instead of guessing.

The practical move for most HVAC and plumbing companies is to work with a small business bookkeeper in Jacksonville who understands how trades businesses run. Generic bookkeeping produces financial statements that are technically accurate but operationally useless. You need books structured around the way your company actually makes and spends money so you can bid better, manage cash flow through slow seasons, and avoid surprises when tax time comes around.