September 30, 2026 · Mitt Patel · 6 min read
Payroll hits next Friday, the last big install got paid two weeks ago, and the phone has gone quiet now that it's April. You check the bank balance and it looks fine today. The question that matters isn't today, though. It's whether it still looks fine in six weeks, after two payrolls and a supplier bill you forgot was coming.
Why the squeeze sneaks up on you
Heating and cooling work is seasonal, but the books aren't built to show seasonality coming. QuickBooks tells you what already happened: invoices sent, payments received, bills paid. It doesn't tell you that shoulder months between the summer cooling rush and the winter heating season, often May and October in many regions, are when cash usually gets tight for HVAC companies. Revenue slows down while payroll, insurance, and loan payments keep going on the same schedule they always do.
Most owners feel the squeeze about two weeks before it happens, when they notice the balance dropping faster than expected. By then the choices are narrow: delay a supplier payment, put off hiring the technician you needed for summer, or draw on a line of credit you weren't planning to use. None of those are wrong, but making them on short notice is worse than making them with six weeks of notice.
The real cost isn't the tight month itself. It's the decisions made under pressure that a person with more lead time wouldn't make. Skipping a marketing push right before the busy season starts because cash feels tight, or turning down a good hire because payroll looks scary next month, even though the season about to start would easily cover it.
A 13-week cash forecast fixes this by turning "what already happened" into "what's about to happen." It's not complicated, and it doesn't require new software. It takes about an hour a month once you've set it up, using numbers you already have in QuickBooks.
A worked example
Say you run a small HVAC company with two crews. Right now it's the first week of April, and your bank balance is $40,000.
You know that over the next four weeks:
- You expect $60,000 in customer payments, based on invoices already sent and jobs scheduled.
- Payroll runs every other week at $18,000 per run, so two runs total $36,000.
- A supplier payment of $8,000 is due in week three, for parts already ordered.
- A loan payment of $2,000 comes out automatically every month.
- Rent and insurance together run $4,000 a month.
Add up the outflows: $36,000 in payroll, $8,000 to the supplier, $2,000 loan payment, $4,000 in rent and insurance. That's $50,000 going out.
Against $60,000 coming in, you'd end the four weeks with a $10,000 cushion on top of your starting $40,000, putting you at $50,000, before accounting for the slow-paying commercial jobs below. That looks fine.
But say $15,000 of that expected $60,000 is from two commercial jobs that always pay slow, and there's a real chance they land in week six instead of week four. Now your four-week cash in is $45,000 against $50,000 out. The month you expected to add $10,000 takes $5,000 out instead, and you end near $35,000 rather than $50,000. Nothing about today's balance tells you that. Once you extend it to 13 weeks, you can see whether that dip is a one-week timing gap that fixes itself, or the start of the shoulder-month squeeze where the next two months of expected revenue are also lighter than payroll and fixed bills.
That's the entire value of the forecast: not predicting the future perfectly, but seeing a gap five or six weeks before it arrives instead of finding out from the bank balance the week it happens.
How to set it up
- Pull your recurring outflows first. Open QuickBooks and list every payroll date, loan payment, lease payment, insurance premium, and recurring supplier bill for the next 13 weeks. These are the most predictable numbers you have, so start here.
- List expected inflows by week, not by month. Go through open invoices and scheduled jobs. For each one, put a realistic collection week next to it, not the invoice date. If a customer type reliably pays in 30 or 45 days instead of on receipt, use that pattern instead of the invoice terms.
- Build a simple spreadsheet with 13 columns, one per week. Row one is starting cash. Row two is expected cash in. Row three is expected cash out. Row four is the ending balance, which becomes next week's starting balance.
- Separate reliable revenue from uncertain revenue. Recurring maintenance contracts and residential jobs with deposits are more predictable than large commercial invoices. Flag the uncertain ones so you can see how the forecast changes if they slip a few weeks.
- Update it weekly for the first month, then monthly. The first few weeks teach you how accurate your collection assumptions are. Once the pattern holds, checking in monthly and adjusting the next few weeks is usually enough.
- Compare forecast to actual every week you update it. If customers are paying two weeks later than you assumed, or a supplier moved to shorter terms, adjust the model. The forecast is only useful if it reflects how the business actually behaves.
What undoes it
A few habits quietly make the forecast useless, even after it's built:
- Using invoice date instead of expected payment date. If a customer always pays three weeks late, put the payment three weeks out. Optimistic dates defeat the whole purpose.
- Forgetting irregular but predictable costs. Annual insurance renewals, a new truck payment, or a seasonal bonus can blow a hole in the forecast if they're not on the calendar.
- Letting it go stale. A forecast built once in April and never touched again is just a guess by June. It needs a standing time slot, even fifteen minutes, to stay accurate.
- Mixing personal and business transfers into the numbers. If money moves between a personal account and the business account, keep it separate from the operating cash forecast, or note it clearly, so the picture isn't distorted.
- Ignoring the gap between "invoiced" and "collected." Revenue on the books isn't cash in the bank yet. The forecast should only count money once you have a realistic date it will actually land.
Monthly checklist
- Update the 13-week forecast with the latest bank balance and any new invoices or jobs scheduled.
- Review any commercial or slow-paying invoices and confirm the expected collection week is still realistic.
- Check upcoming payroll dates against the calendar for any extra pay periods or seasonal bonuses.
- Confirm supplier bills and loan payments due in the next four weeks match what's in QuickBooks.
- Note any weeks where cash out is close to or higher than cash in, and flag them for follow-up.
- Compare last month's forecast to what actually happened, and adjust assumptions that were off.
Common questions
How is this different from the cash flow statement QuickBooks already generates?
The standard cash flow statement in QuickBooks reports on a period that has already happened. A 13-week forecast is forward-looking and week-by-week, built from invoices, scheduled jobs, and known recurring payments that haven't happened yet. They answer different questions: one shows where you've been, the other shows where you're headed.
Do I need special software to build this?
No. A spreadsheet works well, and the inputs come straight out of QuickBooks: open invoices, recurring bill schedules, and payroll dates. Some owners eventually connect a cash flow tool to QuickBooks for convenience, but it's not required to get the benefit.
How far out should I really trust the numbers?
The first four to six weeks are usually fairly reliable, since most of those payments and invoices are already known. Weeks eight through thirteen are more of a planning guide than a prediction, useful for spotting a pattern like the shoulder-month squeeze rather than pinning down an exact balance.
What do I do once the forecast shows a shortfall?
That depends on the size of the gap and the reason behind it, and it's worth thinking through with someone who knows the business. Options generally include timing a supplier payment differently, following up on slow-paying invoices earlier, or lining up a short-term option before the gap arrives rather than after.
North Hudson Bookkeeping builds this forecast into your monthly bookkeeping and keeps it updated from your QuickBooks numbers, so you see the shoulder-month squeeze coming instead of finding it in the bank balance. The first call is free.
