The 13-Week Cash Flow Forecast: Your New Best Friend

"Can I afford this truck?" "Should I hire another tech?" "Do I have enough to cover quarterly taxes?"

If you're answering these questions by checking your bank balance and guessing, you're doing it wrong. And you're not alone—most contractors run on gut feel when it comes to cash.

There's a better way: the 13-week rolling cash flow forecast. It's the single most important financial tool I give my fractional CFO clients. Here's how it works and how to build one.

Why 13 Weeks?

Thirteen weeks is one quarter—90 days. That's long enough to see around the corner on major expenses (quarterly taxes, insurance renewals, equipment payments) but short enough to forecast with accuracy.

Anything longer than 13 weeks becomes a guess. Anything shorter doesn't give you enough runway to make decisions.

The Basic Structure

Your 13-week cash flow is a simple spreadsheet with columns for each week and rows for:

Cash In:

Expected collections (based on AR aging and historical pay patterns)
New job deposits
Service revenue
Any other income (equipment sales, rebates, etc.)

Cash Out:

Payroll (including taxes)
Materials and supplies
Subcontractors
Rent/mortgage
Vehicle payments
Insurance
Loan payments
Owner draws
Quarterly tax estimates

Starting cash + Cash in – Cash out = Ending cash

That ending cash becomes next week's starting cash. Roll it forward every week, and you always have a 90-day view.

The Magic: What It Shows You

When you build this out, you'll immediately see things like:

Week 6 is going to be tight. Quarterly taxes hit, but that big GC payment probably won't land until Week 8.
You CAN afford the truck—but only if you push the first payment to Week 10.
You need to collect that $45K invoice NOW, or Week 4 payroll is a problem.

This is the difference between reacting and planning. Without a 13-week forecast, you find out about cash problems when they happen. With one, you see them coming and can do something about it.

How to Build It (The Simple Version)

Start with today's bank balance. That's your Week 1 starting cash.
List your known outflows. Payroll dates, loan payments, rent—anything with a fixed date and amount.
Add your variable outflows. Estimate materials, subs, fuel based on recent history and scheduled jobs.
Project your collections. Look at your AR aging. If a customer typically pays in 45 days, put that invoice in the week it's likely to hit.
Update it every week. This is crucial. A 13-week forecast is only useful if it's current. Every Monday, roll it forward and update actuals.

Common Mistakes

Being too optimistic on collections. If a customer is slow, don't assume they'll suddenly pay fast. Use their actual pattern.

Forgetting irregular expenses. Annual insurance renewals, quarterly taxes, license renewals—these surprise people who don't plan for them.

Not updating it. A stale forecast is worse than no forecast. It gives you false confidence. Commit to updating it weekly.

The Payoff

Once you have a 13-week cash flow running, you'll notice something: the stress drops.

Not because cash problems disappear—they don't. But because you see them coming. You have time to collect, negotiate, delay, or plan. You stop living in reactive mode.

And when your banker asks how your cash position looks? You can answer with actual numbers, not a shrug.

"I don't know if I can make payroll" is a terrifying sentence. "Payroll is tight in Week 6, but I have a plan" is a business decision.

That's the difference a 13-week forecast makes.