Stop Guessing Your Cash: See 13 Weeks Ahead

Contractors do not go under because of bad jobs on paper; they go under because they run out of cash. Payroll is due Friday. A big material order just hit your card, your subcontractors want their draw, and the retainage you thought would arrive is still on hold. Without a clear view of cash in and cash out, every week feels like a guessing game.

A rolling 13-week cash forecast gives you a simple, practical way to see your cash runway week by week. Instead of just looking at an annual budget, you get a living tool that shows when money will actually hit the bank and when it will leave. That matters in construction because of uneven progress billings, slow-paying generals or owners, change orders, and retainage.

In this article, we will walk through how a 13-week cash forecast works, what the template should look like, the weekly inputs you need, and how to tie it into your WIP schedule and AR aging. The goal is to give you a clear, contractor-friendly system so you can stop guessing and start planning.

Why Contractors Need a 13-Week Cash Forecast

Construction cash flow is lumpy by nature. You often pay for labor and materials long before you collect from the owner or GC. On top of that, you deal with upfront material orders and delivery, mobilization costs and equipment moves, subcontractor draws and pay-when-paid issues, retainage that sits for months, and seasonal slowdowns and ramp-ups.

A 13-week view gives you enough time to see trouble coming and adjust. Instead of getting surprised by a tight payroll week, you can see it six or eight weeks ahead and plan your billings, collections, or line of credit use.

It also lets you line up big items like:

• Payroll and payroll taxes  

• Equipment rentals and fuel  

• Quarterly tax estimates  

• Insurance premiums and license renewals  

When you tie this to good construction business accounting, you stop looking only in the rearview mirror. Job cost reports show if work is profitable. The 13-week cash forecast shows if you can actually fund the work. Owners and project managers get a fuller picture: which jobs make money and which weeks might be tight on cash.

Core Structure of a Rolling 13-Week Template

The good news is the basic layout is simple. Think of a spreadsheet with:

• Columns across the top: Week 1 through Week 13  

• Rows down the side: beginning cash, inflows, outflows, and ending cash  

From there, the template usually breaks into inflows and outflows. Inflows are the ways cash arrives in the bank during the week, while outflows are the payments and withdrawals that reduce your available cash.

Key inflow categories include:

• Customer receipts from progress billings  

• Retainage releases  

• Approved change orders billed and collected  

• Service and maintenance work receipts  

• Line of credit draws  

• Owner or investor contributions  

Key outflow categories include:

• Payroll, payroll taxes, and benefits  

• Subcontractor payments  

• Material and supplier payments  

• Equipment rentals and repairs  

• Job-related costs not run through payroll  

• Overhead (rent, utilities, software, insurance)  

• Debt service and interest  

• Tax payments  

• Owner distributions  

Each week has a beginning cash balance. You add all inflows, subtract all outflows, and that gives you an ending cash balance. That ending balance becomes the beginning cash for the next week.

The “rolling” part means you never let it go stale. At the end of each week, you drop the week that just passed and add a new week at the far end. You always keep 13 weeks visible, so you are always looking about three months ahead.

Weekly Inputs You Must Update

A 13-week forecast only works if it is fed with current job and accounting data. The good news is you do not need to rebuild it from scratch each time, you just refresh the key inputs.

Most contractors can run this with a short weekly routine, using:

• Updated WIP schedule  

• AR aging report  

• AP and subcontractor payables  

• Payroll calendar and estimates  

• List of upcoming tax, loan, and insurance payments  

To keep the forecast credible, you will update the items that change most often. That includes what cash actually hit the bank, what receipts moved due to billing or approval delays, and which vendors or subs are realistically getting paid in the next week or two.

What should be updated weekly:

• Cash actually collected by customer and job  

• Timing of expected receipts from progress billings and change orders  

• Which vendors and subcontractors will be paid this week or next  

• Exact payroll numbers, including overtime if needed  

• New jobs awarded and expected billing dates for early phases  

Some inputs can be refined less frequently because they tend to be more stable. You still want them represented in the 13-week view, but you do not need to rework them every single week unless something changes.

What can be refined monthly:

• Overall revenue assumptions for later weeks  

• Broader overhead estimates  

• Any changes to debt service or regular draws  

Plan on 30 to 45 minutes each Monday to:

• Enter last week’s actual cash activity  

• Adjust the next few weeks for any delays or accelerations  

• Confirm payroll amounts and timing  

• Add any new jobs or major change orders  

Field and project managers should have a voice in the dates. They know when a slab will really pour, when an inspection is likely to happen, or when a change order will be ready to bill. That keeps the forecast grounded in job reality, not just accounting guesses.

Tying Your Forecast to WIP and AR Aging

To move from rough guesswork to a stronger forecast, you need to link your 13-week view to your WIP schedule and AR aging. The WIP schedule helps you predict what should be billed and when, while AR aging helps you estimate when billed amounts are likely to turn into real cash.

Using the WIP schedule:

• Take projected billings from active jobs  

• Map them into specific weeks based on contract terms and percent complete  

• Use billing cycles in your contracts, like monthly AIA billings or milestones  

• Adjust when WIP shows a job is underbilled, since that means you are funding work with your own cash  

Using the AR aging:

• Look at current, 30, 60, and 90+ day buckets  

• For each large balance, assign a likely collection week based on past behavior for that GC or owner  

• Shift expected cash receipts out if you know a customer is slow or if there are unresolved punch list items  

When you connect WIP and AR to the forecast, you create a practical feedback loop that makes the model more accurate over time. As jobs slip, approvals drag, or customers pay slower than expected, the forecast updates and shows you the real downstream impact on cash.

This creates a feedback loop:

• When WIP shows a job slipping, push billings and cash receipts further out in the forecast  

• When AR stretches, move those inflows into later weeks and see the impact on your ending cash  

• If cash gaps appear, plan earlier conversations about change order approvals, billing timing, or line of credit use  

Good construction business accounting means you are not just applying a flat percentage to revenue. You are tying cash to specific jobs, contracts, and customers. That makes your 13-week forecast something you can explain and defend to your team, your bank, and your bonding company.

Using the Forecast for Better Decisions

Once your 13-week cash forecast is in place, it becomes a tool for real decisions, not just a spreadsheet that sits on a server.

You and your CFO, controller, or managed accounting team can use it to plan:

• When to add a crew or delay a hire  

• Whether an equipment purchase should be now or later  

• Timing of owner distributions so they do not starve the business  

• How and when to draw on or pay down a line of credit  

Banks and bonding companies tend to respond well when a contractor can show a short-term cash plan tied directly to WIP and AR. It signals that you know your numbers and that your projects are being managed both in the field and in the office.

Seasonally, a 13-week forecast helps around busy ramps, like spring and early summer:

• Planning overtime for crews when work spikes  

• Scheduling pre-buys of materials without choking cash  

• Timing tax deposits so they do not land in the same week as big mobilization costs  

Over time, this steady weekly review builds better habits across your whole company. Project managers think more about how billing and change order timing affects cash. Owners feel less pressure from surprise crunches and can focus more on bidding and operations.

Put Your 13-Week Cash Plan to Work Now

You do not need a perfect model on day one. Start simple. Build a basic spreadsheet with 13 columns, list your main cash in and cash out categories, then map the next four weeks using your current WIP and AR aging. Once that feels solid, extend it out to the full 13 weeks.

Assign someone as the “owner” of the forecast and hold a short weekly finance huddle to review it. Look at the low points in cash, talk about what changed from last week, and decide what actions to take. As you go, you can add more detail, refine your categories, and bring in your accounting support to tie it even more closely to your job data.

Strengthen Your Construction Finances With Expert Support

If you are ready to bring clarity and control to your job costs, cash flow, and profit margins, our team at Builders Tax Group is here to help. Explore how our specialized construction business accounting services can streamline your books and free you up to focus on building. We tailor our approach to your projects, systems, and long-term goals so you always know where your numbers stand. Have questions or want to talk through your situation first? Just contact us to schedule a conversation.