By Adam Hicks, CooperBuild AI · November 7, 2026

A construction cash flow forecast is a week-by-week plan of the cash you expect to collect and pay out over the next few months, built job by job. Most GCs use a rolling 13-week forecast: owner receipts go in the week each owner actually pays, and payroll, subs, materials, retainage and overhead go in the week they leave the bank. The number that matters is the lowest weekly balance, because that's where you run short.

A job can be profitable on paper and still drain your account. You pay crews every week and subs every month, then wait on owners who pay 30, 45 or 60 days after you bill. This guide shows how to build the forecast, what to put in each line, and how to keep it honest week to week. For the billing side, see our guide on how to get paid faster in construction.

#Why do profitable contractors run out of cash?

Profit and cash run on different clocks. Your P&L counts revenue when you bill or earn it. Your bank account only counts it when the owner's check clears.

The usual gaps:

• Payment lag. You front labor, materials and subs, then wait on the owner's review and payment cycle.
• Retainage. A slice of every pay app sits with the owner until substantial or final completion. See retainage in construction.
• Unbilled changes. Work done on a verbal or emailed change that hasn't made it onto a pay app yet is cash you've spent and can't collect.
• Growth. Two new profitable jobs can open a bigger cash hole than one smaller job, because the costs start weeks before the first receipt.

That's why contractors in recent r/ConstructionManagers and r/GeneralContractor threads keep landing on the same answer: a rolling 13-week forecast by job, updated every week, instead of looking at cash once a month when it's already too late.

#Why 13 weeks?

Thirteen weeks is one quarter. It's long enough to see a shortfall coming six or eight weeks out, while you can still do something about it: chase an owner, move a billing date, delay a distribution, or draw on a line of credit on your terms. It's also short enough that your numbers are based on real pay apps, real sub schedules and real payroll, not guesses about jobs you haven't won.

Many GCs keep a rougher 6- to 12-month view next to it for bidding and hiring decisions. The 13-week forecast is the one you run the business on.

#How do you build a 13-week cash flow forecast?

Set it up in a spreadsheet with one column per week and these rows.

#1. Start with real cash

• Beginning cash: your actual bank balance on the day week 1 starts.
• Cash minimum: the balance you never want to drop below. Many owners set it at one to two months of overhead; pick a number that matches your payroll and your risk tolerance.

#2. Forecast receipts by job

For each active job, list every pay app you expect to submit and put the payment in the week that owner usually pays, not the week the contract says. Use your own collection history. If an owner's AP always runs two weeks late, forecast two weeks late.

Separate lines for:

• Progress billings, net of retainage held
• Retainage releases (only when you have a realistic release date)
• Approved change orders, in the pay app they'll actually be billed on
• Deposits or mobilization payments

#3. Forecast disbursements by week

• Payroll and burden on its real cycle, including payroll taxes, union fringes and workers' comp
• Subcontractor payments net of the retainage you hold. If your subcontracts are pay-when-paid, tie each sub payment to the week of the owner receipt it depends on
• Materials and suppliers on their actual terms
• Equipment rentals and payments
• Overhead: rent, insurance, software, vehicles, office salaries
• Debt service, taxes and owner distributions

Committed costs are your best input here. Signed subcontracts and approved POs tell you what's coming even before invoices arrive. Our guide on committed costs vs actual costs covers how to track them.

#4. Read the low point first

Net cash flow is receipts minus disbursements. Ending cash carries forward to the next week. Then find the lowest ending balance across all 13 weeks and the week it happens. If any week drops below your cash minimum, you now know which week, which job is driving it, and roughly how much you're short.

#What do you do when the forecast shows a gap?

Work the receipts side before you reach for debt:

• Bill everything you can. Get approved change orders onto the next pay app instead of waiting for a "clean" month. See our change order process guide.
• Make pay apps hard to reject. Missing backup, waiver problems or a schedule of values that doesn't tie out can push payment a full cycle.
• Call slow owners early. A phone call two weeks before the low point beats a collections email after it.
• Bill stored materials where the contract allows it.
• Align sub terms. Pay-when-paid and matching retainage percentages keep your payables in step with your receivables, where your contracts and state law allow.

If there's still a gap, a construction line of credit sized from the forecast is cheaper and calmer than a surprise draw. Some contractors use factoring; weigh the fees carefully.

#How do you keep the forecast accurate?

The forecast is only useful if you update it every week. Most owners who give up on cash forecasting stop because updating it by hand is a chore.

A simple weekly routine:

1. Roll it forward. Drop the week that just ended and add a new week 13.
2. Replace forecast with actuals. Compare what you expected to collect and pay with what really happened.
3. Note why it was off. A late owner, a pay app rejected for missing backup, a sub who billed early. Those notes improve next week's timing.
4. Check billing readiness mid-month. Around the 15th, look at which approved changes are still unbilled and which sub pay apps and waivers haven't come in, so the end-of-month pay app goes out complete.

Tie it to your WIP schedule once a month. If a job is underbilled on the WIP, that's cash you've earned but haven't asked for yet. Our construction WIP report guide shows how to read it.

#Where CooperBuild AI fits

The hard part of a cash forecast isn't the spreadsheet. It's gathering the inputs: pay apps from one system, subcontracts from another, payroll from a third, and the bank balance from QuickBooks. CooperBuild AI keeps estimates, budgets, change orders, billing and built-in accounting (GL, AP and AR) in one place, connects to QuickBooks Online if that's where your books live, and accepts owner payments through integrated Stripe payments. With receivables, commitments and payables in one system, your assistants can help you pull the numbers for your weekly forecast instead of you chasing them across files.

If you want your billing and costs in one place before the next tight month, get started with free credits, no credit card needed.

#FAQ

#What is a construction cash flow forecast?

It's a week-by-week projection of the cash a contractor expects to collect from owners and pay out for payroll, subs, materials, overhead and debt, usually built job by job. It shows when the bank balance will be lowest so you can act before you run short.

#Why do contractors use a 13-week cash flow forecast?

Thirteen weeks is one quarter, long enough to see a shortfall several weeks ahead and short enough to be based on real pay apps, sub schedules and payroll rather than guesses about future work.

#How is a cash flow forecast different from a WIP report?

A WIP report compares billings to earned revenue on each job to show overbilling and underbilling. A cash flow forecast shows when money actually moves in and out of the bank. Underbilling on the WIP often explains a cash gap in the forecast.

#How should retainage be handled in a cash flow forecast?

Forecast progress billings net of the retainage the owner holds, and list retainage releases separately in the week you realistically expect them. On the payables side, forecast sub payments net of the retainage you hold.

#How often should a contractor update a cash flow forecast?

Every week. Roll it forward one week, replace last week's forecast numbers with actuals, and note why anything was off so your payment timing gets more accurate.

This article is general information for contractors, not accounting, tax, legal or financial advice. Confirm payment, retainage and lending terms in your contracts and with your CPA or lender.