The short answer
HVAC contractors run out of cash in summer because revenue and cash are not the same thing. During peak season you buy equipment and pay techs up front, but customer payments, especially from commercial accounts, arrive weeks later. Add fast inventory spending and a low cash cushion left over from a slow spring, and a record-breaking July can still leave you scrambling to make payroll. The fix is a simple cash flow system: forecast ahead, get paid faster, and set money aside before the busy rush burns it.
This trips up almost every contractor at some point. The calendar is packed. The trucks are out from dawn to dark. Invoices are flying. And the bank balance is dropping.
Here is why. The day you install a system, you have already paid for the equipment, paid your supplier, and paid the techs who did the work. The customer, though, has not paid you yet. On a residential job that gap might be a few days. On a commercial job it can be 30, 60, even 90 days. Meanwhile the next job needs equipment ordered today. You are funding everyone else's project with your own cash and waiting to be paid back.
Multiply that across a July where you are running every truck you own, and the math gets tight fast. Revenue on paper looks great. Cash in the account tells a scarier story.
Every one of those steps is normal. The danger is having no system sitting underneath them.
A cash flow forecast is a simple projection of money coming in and going out over the next 90 days. It is not a budget and it is not your P&L. It answers one question: will I have enough cash on a given week to cover what is due. Run a base case, a best case, and a worst case so a slow collection month does not blindside you. This is the single highest-value habit in the list.
The crunch is a timing problem, so attack the timing. Collect deposits on installs before you order equipment. Send invoices the day a job closes, not at the end of the month. Make it easy to pay you online. Put real terms on commercial accounts and follow up the day an invoice goes past due. Money you earned in June does you no good if it lands in September.
The best time to build a reserve is the back half of spring, before summer eats it. A reserve of a few weeks of operating expenses is the difference between a stressful week and a missed payroll. Treat it like a bill you pay yourself.
Aging receivables are the quiet killer. Pull an AR aging report weekly during busy season and chase anything past 30 days. In the trades, the squeaky wheel gets paid. The contractor who calls the day after the due date collects faster than the one who waits and hopes.
Sales tax you collect is not your money, and a chunk of your profit belongs to the IRS. Moving that out of your operating account as it comes in keeps you from spending money you will owe back later. Few things wreck a good year faster than a tax bill you already spent.
Down here, the heat does not wait politely for June. A hot stretch in April or May can flip the switch on your busy season early, which means your spending spikes before you have rebuilt any reserve from the slow months. The Louisiana climate also stretches your cooling season longer than most states, so the cash gap runs wider and longer. Forecasting is not a nice-to-have in this market. It is how you survive your own success.
| Spend | → | Work | → | Wait | → | Collect |
What is cash flow forecasting for an HVAC business?
It is a projection of the cash you expect to receive and spend over a set period, usually the next 90 days, so you can see ahead of time whether you can cover payroll, suppliers, and bills.
Why do HVAC contractors have cash flow problems even in busy season?
Because cash goes out for equipment and labor before customers pay, and the lag between the two creates a gap. Heavy summer volume makes the gap bigger.
How much cash should an HVAC company keep in reserve?
A common starting target is a few weeks to a couple of months of operating expenses. The right number depends on how long your customers take to pay and how seasonal your revenue is.
How can I get my HVAC customers to pay faster?
Collect deposits on installs, invoice the day the job closes, offer online payment, set clear terms on commercial accounts, and follow up the moment an invoice goes past due.
Jeremy Brewer is the founder of 911 Bookkeepers LLC in Baton Rouge, Louisiana. He came up as an HVAC field tech and works as a licensed paramedic in EMS. He is a Xero Certified Advisor. 911 Bookkeepers is built for the trades.
Related posts in this series: HVAC Bookkeeping: The 12 Numbers · Revenue vs. Profit · Mid-Year Financial Check-Up
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