Most HVAC owners start out as good technicians, and the books come later. Rodney Koop, founder and CEO of The New Flat Rate, told ACHR News what happened when he bought his first company:
I quickly ran up my costs, and my bill to my distributor exceeded $45,000. None of the money I made went toward my bills.
Pete Peterman, founder of Peterman Brothers in Beech Grove, Indiana, described the same blind spot in the same article:
I didn't really focus on the company's accounting. I based everything on the deals we were making and only focused on covering our weekly expenses. Knowing our numbers and utilizing KPIs [key performance indicators] would have certainly made things easier.
Most guides on bookkeeping for HVAC contractors are written for $2 million to $10 million companies with an office manager. This one is for the shop with 1 to 20 techs, where the owner is also the estimator and the books happen on a phone in the truck. It covers the three places small-shop books usually go wrong: job costing, parts receipts, and maintenance agreements.
Bookkeeping for HVAC contractors: the short answer
Good HVAC bookkeeping means three things: separate income by the kind of work, tie every equipment and parts cost to a job, and treat prepaid maintenance agreements as a liability until you do the visits. Add monthly bank reconciliation and you can answer the only question that matters: which jobs actually make money.
A chart of accounts sized for a small shop
A chart of accounts is the list of categories your books use. Big-shop templates run to dozens of lines. A 1 to 20 tech shop needs roughly this:
| Section | Account | What goes in it |
|---|---|---|
| Income | Service and repair | Diagnostic fees, repairs, parts sold on service calls |
| Income | Replacement installs | System replacements and new equipment jobs |
| Income | Maintenance agreements | Agreement revenue as visits are completed |
| Income | Warranty reimbursements | Labor or part credits from manufacturers and distributors |
| Job costs | Equipment | Condensers, furnaces, air handlers, heat pumps |
| Job costs | Parts and materials | Supply-house purchases used on jobs |
| Job costs | Subcontractors | Electrical, ductwork, crane, and other subs |
| Job costs | Field labor | Tech wages and payroll taxes on billable work |
| Job costs | Permits and disposal | Permit fees, refrigerant recovery, haul-away |
| Overhead | Vehicles and fuel | Truck payments, fuel, maintenance, insurance |
| Overhead | Tools and equipment | Gauges, vacuums, recovery machines, small tools |
| Overhead | Insurance, rent, software, marketing | The cost of keeping the doors open |
| Balance sheet | Deferred agreement revenue | Prepaid visits not yet done (a liability) |
| Balance sheet | Customer deposits | Install deposits received before the job |
| Balance sheet | Sales tax payable | Tax collected that belongs to the state |
Splitting income this way is what lets you see that installs carry the year while service calls cover the slow months, or the other way around. One owner's warning, from the same ACHR News piece: "Profit on paper is not money filling a bank account." The categories are how you find out where the money actually went.
Job costing a small shop can actually do
Job costing means tracking what each job cost you against what you charged for it. You don't need software built for $10 million contractors. You need every cost to carry a job name.
Track per job: equipment, parts, subcontractors, labor hours times your loaded labor rate, and permits or disposal. Here is a worked example for a replacement install (the numbers are illustrative):
| Line | Amount |
|---|---|
| Price charged | $9,800 |
| Equipment | $4,100 |
| Parts and materials | $650 |
| Labor: 16 hours at $45 loaded | $720 |
| Permit and disposal | $150 |
| Gross profit | $4,180 (42.7%) |
Do this for every install and a sample of service calls each month, and patterns show up fast: a type of system you always underbid, a tech whose jobs run long, a supply house that's quietly more expensive.
Getting the cost into the right bucket matters as much as recording it. Greg Crumpton, who founded AirTight Mechanical, described the problem his company hit to ACHR News:
The problem was in how we were reporting whether the material we bought was going to a project for a fixed cost or was a time-and-material repair
A fixed-price install and a time-and-material repair use the same parts but tell you completely different things about profit. Tag the job, not just the expense.
Parts receipts: the routine that keeps job costing honest
The weakest link in most small-shop books is the supply-house ticket that lives in the truck console until April. A routine that works:
- Name the job on every ticket, the day you buy the part. A photo of the receipt with the customer name or job number is enough. Parts bought to restock the truck get "truck restock" instead.
- Match returns and counter credits to the original job. A returned part that isn't matched makes one job look expensive and another look cheap.
- Book warranty part credits. When a distributor credits you for a failed part, record the credit against that job's parts cost or under warranty reimbursements, so a warranty callback doesn't show up as a loss.
- Keep the receipts. The IRS's basic rule is to keep records for 3 years from filing, longer in some situations, and 4 years for employment tax records (IRS).
Truck stock. If you carry a meaningful amount of parts on each truck, track it as inventory and count it on a schedule, quarterly is common, so the cost moves to jobs as parts are used. Smaller shops often expense parts when they buy them. The IRS has a small business exception for how inventory is treated for taxes, covered in Publication 538; your CPA can tell you which way fits.
Maintenance agreements: money you owe in visits
When a customer pays upfront for a year of maintenance, you haven't earned that money yet. You owe them visits. On the books, that prepayment is a liability, usually called deferred revenue, and it becomes income as you do the work.
A worked example: a customer buys a $240 plan in March with a spring and a fall tune-up.
| When | Cash | Deferred agreement revenue (owed) | Agreement income |
|---|---|---|---|
| March: customer pays | +$240 | $240 | $0 |
| May: spring tune-up done | $0 | $120 | $120 |
| October: fall tune-up done | $0 | $0 | $120 |
Without this, a shop that sells a lot of agreements in spring looks wildly profitable in March and like it's losing money in October. With it, each month shows the work actually done that month.
For taxes, the rule is different. The IRS says that generally "you report an advance payment for goods, services, or other items as income in the year you receive the payment," and that if you use an accrual method, you can elect to postpone it until the next year, but no further (IRS Publication 538). Keeping the books on deferred revenue for decisions while your CPA handles the tax treatment is normal.
Financed installs and lender fees
When a customer finances a system through a lender, the lender usually pays you the price minus a fee. Book it in two pieces so your revenue isn't understated:
- Income: the full price of the job, say $10,000.
- Expense: the lender's fee, say $600, under a financing fees account.
- Deposit: the $9,400 the lender sends, matched against the customer's invoice.
Recording only the $9,400 hides the fee, and the fee is a cost you can negotiate or price in.
Sales tax on parts and labor depends on your state
There is no national rule for HVAC. Some states tax repair labor, some don't, and many treat residential and commercial work differently. Texas, for example: "Labor to repair, remodel, or restore residential real property is not taxable," while "The total amount charged for remodeling, repairing, or restoring nonresidential real property is taxable" (Texas Comptroller). The SBA's advice is to "check with state and local governments to know your business' tax obligations," and it keeps a directory of state revenue departments (SBA). Whatever your state's rule, keep sales tax you collect in its own account. It isn't income.
Heat pump customers asking about the federal credit: the IRS says the 25C energy efficient home improvement credit "will not be allowed for any property placed in service after December 31, 2025" (IRS). Sales sheets printed before that change may still mention it.
Subcontractors and 1099s
Get a W-9 from every sub before you pay them. For payments made in 2026, you file a Form 1099-NEC for a non-employee you paid $2,000 or more for services, due January 31 (IRS instructions for Forms 1099-MISC and 1099-NEC). Payments to incorporated businesses are generally exempt, with exceptions such as legal services. Older guides still say $600, which was the threshold for decades.
Cash flow through the seasons
HVAC cash swings with the weather. A few habits smooth it:
- Pay suppliers as jobs close. Koop's advice after his $45,000 distributor bill: "Once a job is done, it's nice to pocket that money, but make sure you pay your equipment expenses right away."
- Set aside tax money from every payment, in a separate account. Ask your CPA what share.
- Sell maintenance agreements in the shoulder seasons. They bring in cash when calls are slow and fill the schedule before peak.
- Chase late invoices weekly, especially commercial ones. Our guide on how to follow up on an overdue invoice has the scripts.
A monthly routine for a small shop
| When | What |
|---|---|
| Every day | Photograph supply-house tickets with the job name |
| Every week | Send invoices for finished jobs; follow up on late ones |
| Every month | Reconcile every bank and card account; move earned agreement revenue to income; review job costs on installs |
| Every quarter | Count truck stock; review sales tax filings; check estimated taxes |
| Every January | Send 1099-NEC forms to subs paid $2,000 or more in 2026 |
Where Ruth fits
The daily and monthly rows of that table are where Ruth helps. Ruth is Clef's AI bookkeeper, and she works by text. Snap the supply-house ticket and text it to her, and she files it and matches it to the payment. She sorts transactions as they come in, asks you about the charges she can't place, closes each month, and prepares your sales tax return for you or your CPA to file. Connecting your bank or QuickBooks is optional. See how Ruth works.
This is general information, not tax or accounting advice. Your CPA can apply it to your shop and your state.
Frequently asked questions
Should HVAC contractors use cash or accrual accounting?
Most small shops can use the cash method for taxes, and many do. Accrual gives a truer monthly picture when you sell maintenance agreements or take deposits, because it books revenue when the work is done. A common setup is to keep the books on accrual for decisions and let your CPA handle the tax method.
How should HVAC maintenance agreements be recorded?
When a customer prepays for visits you haven't done yet, record the money as a liability, often called deferred revenue, and move a share into income as each visit is completed. A $240 plan with two visits becomes $120 of income per visit. For taxes, the IRS generally treats an advance payment as income in the year you receive it.
Do small HVAC shops really need job costing?
Yes, at least a simple version. Tagging every equipment purchase, supply-house receipt, subcontractor bill and labor hour to a job is the only way to know which jobs and which kinds of work make money. A one-truck shop can do it with a job name on every receipt and a monthly report.
What should an HVAC chart of accounts include?
Separate income lines for service and repair, replacement installs, maintenance agreements and warranty reimbursements; job cost lines for equipment, parts, subcontractors, field labor and permits; overhead lines for vehicles, tools, insurance, rent, software and marketing; and balance sheet accounts for deferred agreement revenue, customer deposits and sales tax payable.
How often should an HVAC contractor reconcile their books?
Every month, against every bank and credit card statement. Monthly reconciliation catches missing receipts and miscoded parts while you still remember the job, and it is what a lender or buyer will ask to see.