You're probably losing money on jobs you think are profitable. A practical HVAC accounting guide for solo contractors and small crews.
Most HVAC contractors don't get into the trade because they love accounting. But the contractors who stay in business long-term all have one thing in common: they know their numbers. This guide breaks down HVAC accounting in plain English, with the specifics that actually matter for heating and cooling businesses.
We'll cover the basics (cash vs accrual, what records to keep), the HVAC-specific stuff (job costing, seasonal cash flow, sales tax on parts), the software options, and when it's time to hire help. It's written for solo contractors and small crews, not enterprise CFOs.
Most "small business accounting" advice assumes a predictable, low-cost-of-goods business: a coffee shop, a consulting firm, a software startup. HVAC doesn't fit that mold. Three things make it different:
1. Heavy materials cost on every job. A single AC installation might involve $3,000-$6,000 in equipment and parts before you even count labor. If you can't track materials cost per job, you can't know if a job was profitable.
2. Seasonal cash flow swings. Most HVAC businesses see 60-70% of their revenue in summer (cooling) and winter (heating), with brutal slow periods in between. Your accounting has to plan for the slow months while you're busy in peak.
3. Sales tax on parts you resell. Most states tax parts you install for customers, but the rules vary by state and by the type of work (repair vs. new installation vs. replacement). Getting this wrong creates tax problems that take years to untangle.
These aren't reasons to be intimidated. They're reasons to set up your accounting correctly from day one instead of treating it like an afterthought.
Before any software or strategy, you need to be capturing the data. The IRS requires every business to keep records that support every item of income, deduction, and credit on its tax return. For HVAC contractors, that means:
Keep these for at least three years (the IRS standard) and longer for anything related to assets, payroll, or property. Most contractors keep seven years to be safe.
You have two basic methods:
Cash basis: record income when money hits your bank account and expenses when you pay them. Simple. Most small HVAC businesses use this method.
Accrual basis: record income when you invoice (whether or not you've been paid) and expenses when you incur them (whether or not you've paid them yet). More accurate picture of profitability, but more work.
The IRS allows businesses under $30 million in average annual revenue to use cash basis. For most HVAC contractors, cash basis is the right starting point. Accrual makes more sense once you're consistently doing $1M+ in revenue, or if you have a lot of work in progress at any given time.
A chart of accounts is just a list of every category your money flows through: income, expenses, assets, liabilities. Most accounting software comes with a generic chart, but the contractors who actually use their numbers customize it for HVAC.
A practical HVAC chart of accounts includes, at minimum:
Income accounts:
Cost of goods sold (COGS):
Operating expenses:
Why this matters: if all your revenue is dumped into one bucket called "Service Income," you can't see which services are actually profitable. Separating revenue by service type tells you that maintenance plans are 70% margin and replacement installations are 35%, which changes how you price and market.
Job costing means tracking the exact cost and profit on every job. For an HVAC contractor, this is the difference between knowing your business and guessing.
For each job, you should know:
A target margin for HVAC service work is 40-60% gross margin. Installation jobs tend to run lower (25-40%) because of equipment costs. If you're consistently below those ranges, you're either underpricing or overspending on materials.
You don't need fancy software to job cost. A spreadsheet works for low volume. But you do need to actually do it. The contractors who don't job cost almost always find out later that one of their "best-selling" services was losing money the whole time.
Plug in numbers from a recent job and see if it was actually profitable. Compare your margin to industry targets to know if you're pricing right.
Most HVAC businesses follow a predictable pattern: revenue spikes in summer and winter, drops hard in spring and fall. The mistake most contractors make is spending peak-season revenue as if it's the new normal, then panicking when the slow months come.
A few principles that work:
1. Build a cash reserve. Aim for at least 2-3 months of operating expenses in a separate business savings account. During peak seasons, move a percentage of each deposit there automatically.
2. Set aside taxes immediately. Every dollar of revenue isn't yours. As a rough starting point, set aside 25-30% for federal income tax, self-employment tax, and state taxes. Keep this in a separate account so you're not tempted to spend it.
3. Forecast quarterly, not just annually. A simple monthly cash flow forecast for the next 12 months shows when the lean months will hit and how much you need to bank during peaks.
4. Use the slow seasons strategically. Maintenance plans bill year-round, smoothing your revenue. The slow seasons are also when you should run early-bird promotions for the next peak (March for AC tune-ups, September for furnace tune-ups).
5. Watch your accounts receivable. Unpaid invoices are revenue you "earned" but don't actually have. Aim to collect within 30 days. If invoices are aging beyond that, your collections process needs work.
The fastest way to fix HVAC cash flow problems isn't getting more leads. It's getting paid faster on the work you've already done.
Tactics that move the needle:
Invoice on the spot. Don't go home and "do invoices Friday." Send the invoice before you leave the property, ideally from your phone. Customers are more willing to pay promptly when the work is fresh in their memory.
Accept multiple payment methods. Credit card, ACH, mobile wallet, financing. The more friction-free it is to pay, the faster you get paid. Yes, credit card processing fees cost 2-3%, but a customer who pays the same day at a 3% fee is way better than one who pays in 60 days at zero fee.
Set clear terms. "Due on receipt" or "Net 15" beats "Net 30." For new customers, require deposits (especially on installations) before ordering equipment.
Follow up automatically. Most unpaid invoices aren't from people who refuse to pay. They're from people who forgot. A reminder at day 7, day 14, and day 30 catches most of them. Polite, automated, persistent.
A tool like Tofu handles the customer-facing money flow: send estimates from the job site, convert them to invoices when the work is done, collect payments through the app, and keep a customer-by-customer history of what's been billed and paid. Web app, manager iOS app, and worker app all sync, so whoever's on the job can wrap up the paperwork before they leave. Starts at $10/month for solo contractors and small crews.
Send the invoice before you leave the job site, collect payment on the spot, and keep every customer's billing history in one place. Tofu handles estimates, invoices, and payments for solo contractors and small crews.
The simplest rule: use a dedicated business bank account and a dedicated business credit card. Run every business expense through one or the other. Never mix personal and business.
This isn't just for cleanliness. It's the IRS's first ask in an audit: prove that your business expenses are actually business expenses. Commingled accounts make this nearly impossible.
Common HVAC business deductions that contractors miss:
Track every expense the same week it happens. Snapping a photo of receipts and entering them into your accounting software before they get lost in a glove box is the #1 habit that separates contractors who maximize deductions from those who miss thousands every year.
Tax law changes constantly and varies by state, so this section is general guidance, not specific advice. For your situation, work with a tax professional who knows trades businesses.
That said, here are the basics every HVAC contractor should understand:
Self-employment tax. If you're a sole proprietor, LLC, or partnership, you pay both halves of Social Security and Medicare (15.3% combined on the first ~$168,600 of net earnings, plus 2.9% above that). This is on top of your regular income tax.
Quarterly estimated taxes. The IRS expects you to pay taxes as you earn, not just at year-end. You'll owe quarterly estimated payments (April 15, June 15, September 15, January 15) if you expect to owe more than $1,000 in tax. Miss them and you'll owe penalties.
Sales tax on parts. Most states require you to collect sales tax on materials you mark up and sell to customers as part of a job. Some states tax labor too. Rules vary by state and by job type. Get this right from the start: register for a sales tax permit in your state, charge the correct rate, and file returns on time.
1099s for subcontractors. If you pay any contractor (non-employee) $600 or more in a year, you're required to issue them a 1099-NEC. Collect a W-9 from every subcontractor before you pay them the first time so you have their info when January rolls around.
Entity structure matters. Operating as a sole proprietor is simplest but exposes you to personal liability and may cost more in taxes once you're profitable. Most HVAC contractors form an LLC for liability protection. Some elect S-Corp tax treatment once they're consistently making $80k+ in profit, which can save thousands in self-employment tax. Talk to an accountant before making this change.
Deadlines that matter:
The IRS Small Business and Self-Employed site is the official reference. Don't rely on Reddit threads for tax law.
The accounting software market has three categories that matter for HVAC contractors:
1. General accounting software. Designed for any small business. Handles bookkeeping, reports, tax prep, payroll.
2. Field service software (operations-focused, with invoicing). Handles the customer-facing side: jobs, estimates, invoices, payments, CRM. Usually doesn't replace full accounting software but pairs with it.
3. Construction-specific accounting platforms. Built for contractors with heavy job costing needs. Overkill for most HVAC service businesses, makes more sense for large installation-focused companies.
Realistic stack for most HVAC contractors:
The trap most contractors fall into is trying to use one tool for everything. General accounting software doesn't handle field operations well. Field service software doesn't handle full bookkeeping. The two are complementary, not interchangeable.
For most solo HVAC contractors, doing your own books in QuickBooks or FreshBooks works fine for the first year or two. As the business grows, the math shifts.
Hire a bookkeeper when:
A part-time bookkeeper typically runs $300-1,000/month for a small HVAC business. Worth every penny once you're past the point of doing it yourself reliably.
Hire an accountant (CPA) when:
An accountant for year-end taxes typically costs $800-2,500 for a small HVAC business. Ongoing tax planning runs more but often pays for itself through tax savings.
Don't confuse a bookkeeper with an accountant. A bookkeeper records transactions and keeps your books current. An accountant analyzes them, prepares taxes, and advises on strategy. You'll likely want both eventually.
After looking at many HVAC businesses, the same mistakes show up:
If your accounting is currently a mess of receipts in a glove box and a handwritten ledger, here's the order of operations:
None of this is glamorous. All of it is the difference between an HVAC business that lasts and one that doesn't.
