Cash Flow for Contractors: Why Profitable Shops Run Out of Money

By BRIX Editorial Team · Updated October 12, 2026

Cash flow for contractors is the timing of money in and out of the business: customer payments arriving versus payroll, materials, subs and overhead going out. Contractors usually pay job costs weeks before customers pay them, so a profitable company can still run short of cash. Managing cash flow means shrinking that gap and forecasting it ahead.

Key takeaways

Profit is what a job earns; cash flow is when the money actually moves. You need both.
Most contractor cash crunches come from the gap between paying for labor and materials and getting paid by the customer.
Forecast 13 weeks ahead, week by week. It's the simplest tool that catches a shortfall in time to fix it.
Cash runway = cash in the bank ÷ average monthly net cash outflow. Know yours before slow season.
The fastest fixes: deposits, progress billing, same-day invoicing, collecting on site and matching supplier terms to customer terms.

Why do profitable contractors run out of cash?

Because profit and cash arrive at different times. Your profit and loss statement can show a great month while your bank account is empty, because the P&L counts work you've billed, and the bank only counts money you've collected. Payroll is every week or two. Supply houses want payment in 30 days. Customers, general contractors and insurance companies often take longer. And when you grow, the gap grows with you: more jobs means more costs paid up front.

Worked example: a profitable remodel that drains the account

Illustrative numbers. A remodeling contractor signs a $60,000 kitchen job with a budgeted 30% gross margin: $42,000 in costs, $18,000 in gross profit.

Weeks 1–4: it pays $8,000 for cabinets on order, $12,000 in crew payroll and $6,000 to the plumber and electrician. Cash out: $26,000. Cash in: a $6,000 deposit. The account is down $20,000.

Weeks 5–8: another $16,000 in costs go out. A $24,000 progress payment comes in. Running total: down $12,000.

Week 10: the homeowner pays the final $30,000 two weeks after completion. The job ends up $18,000 ahead.

The job was profitable from day one, but for two months the owner needed up to $20,000 of their own cash to carry it. Take on three of these at once and the business needs $60,000 of cushion it may not have.

How do you calculate cash flow?

Net cash flow

Net cash flow = Cash collected − Cash paid out

Cash collected: customer payments, deposits, loan proceeds and any other money in
Cash paid out: payroll, materials, subs, rent, truck payments, insurance, owner draws, tax payments

Cash runway

Runway (months) = Cash on hand ÷ Average monthly net cash outflow

Runway matters most going into your slow season. A landscaper with $45,000 in the bank who expects to burn $15,000 a month in winter (fixed overhead, equipment payments, keeping a key crew on) has three months of runway: enough for December through February, but not if spring starts late. Run your own numbers with the cash flow runway calculator.

What are the three types of cash flow?

A statement of cash flows splits money movement into three groups. For most small contractors, operating cash flow is the one to watch.

Type	What it includes for a contractor	Healthy sign
Operating	Customer collections minus payroll, materials, subs, rent, insurance and other running costs	Positive over a full year, even if some months are negative
Investing	Buying or selling trucks, equipment, tools and property	Negative when you're investing in growth; that's normal
Financing	Loans received and repaid, equipment financing, owner contributions and draws	Loan payments covered by operating cash, not by new borrowing

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

1
Start with today's bank balance.
Use the actual balance across operating accounts, not what QuickBooks says if it isn't reconciled.
2
List expected collections by week.
Go through your A/R aging report and scheduled progress bills. Put each payment in the week you realistically expect it, not the due date. Late payers stay late.
3
List fixed outflows by week.
Payroll dates, rent, truck and equipment loans, insurance, software, and quarterly estimated tax payments. See quarterly estimated taxes for contractors.
4
Add job-driven outflows.
Material orders, sub payments and equipment rentals for jobs on the schedule. Supplier bills from your accounts payable go in the week they're due.
5
Find the low point.
Calculate the ending balance for each week. The lowest week is your risk. If it dips below one payroll's worth of cash, act now: push for collections, delay a purchase or line up credit.
6
Update it every week.
Drop the week that just ended, add a new week 13 and compare what happened to what you forecast. You'll get better at it within a month.

Cash flow patterns by trade

Where cash gets tight, by trade
Trade	When cash gets tight	What usually helps
HVAC	Spring and fall shoulder seasons; big equipment bills before installs are paid	Maintenance agreements billed monthly; financing paid by the lender at install
Plumbing	Large repipes and new-construction rough-ins billed on long terms	Progress billing on big jobs; collecting on site for service work
Roofing	Storm season, when materials and crews are paid before insurance checks arrive	Deposits where allowed, insurance paperwork done fast, supplier terms matched to job length
Electrical	Commercial subcontracts with monthly billing, pay-when-paid and retainage	Billing on time every month, tracking retainage, closing out jobs quickly
General contractor and remodeling	Mid-job, when costs peak before the next draw	A billing schedule front-loaded to match costs; progress billing
Landscaping and snow removal	Late winter, before spring revenue; equipment purchases	Prepaid seasonal contracts, a winter cash reserve, snow contracts for off-season revenue
Pest control and cleaning	Rarely seasonal; tight when growing fast and hiring	Recurring billing with card on file

Common patterns, not measured statistics.

How can a contractor improve cash flow?

Collect deposits on larger jobs, within your state's rules. See contractor deposit laws.
Bill in stages. On anything longer than a couple of weeks, use progress billing so collections keep pace with costs.
Invoice the same day the work is done, and collect on site for residential service. Our guide on getting paid faster has more.
Chase late invoices on a schedule. Reminders at due date, 7, 14 and 30 days past due. See how to collect unpaid invoices.
Match payment terms. Don't give customers net 45 if your suppliers want net 30.
Sell recurring work. Maintenance agreements smooth out slow months.
Track [days sales outstanding](/learn/days-sales-outstanding) monthly. Use the DSO calculator to see what cutting it would free up.
Separate tax money. Move a share of every deposit into a tax savings account so quarterly payments don't become a cash crisis. See how much to set aside for taxes.
Line up credit before you need it. Banks lend more easily when you don't urgently need the money.

Common cash flow mistakes

Managing from the bank balance. The balance today doesn't show the payroll and supplier bills due next week.
Growing faster than cash allows. Taking on more jobs than your cash can carry is how busy contractors go broke.
Buying equipment with operating cash. Paying cash for a truck can leave nothing for payroll; compare financing with the equipment loan calculator.
Treating customer deposits as profit. A deposit is money for a job you haven't done yet. Spend it on that job.
Ignoring retainage. Five or ten percent held on every commercial job adds up to a big number that won't arrive until closeout.

Frequently asked questions

What is cash flow in construction?

Cash flow in construction is the timing of money coming in from owners, general contractors and customers versus money going out for labor, materials, subs and equipment. Because costs are paid before billing is collected, contractors need to plan for the gap on every job.

Why do contractors have cash flow problems?

Contractors pay crews weekly and suppliers on 30-day terms, while customers often pay 30 to 60 days after work is done, and commercial jobs hold back retainage. Growth makes it worse, because every new job needs more cash up front.

How much cash reserve should a contractor keep?

There's no single right number. A practical starting point is enough to cover fixed overhead through your slowest stretch plus one or two payrolls. Then refine it with your own 13-week forecast and slow-season burn, since seasonality and how fast customers pay change the answer.

What's the difference between profit and cash flow?

Profit is revenue minus expenses for the work you did in a period. Cash flow is the money that actually moved in and out of your bank in that period. You can be profitable with negative cash flow, especially when you're growing or customers pay slowly.

Does progress billing help cash flow?

Yes. Billing in stages as work is completed means you collect while costs are being incurred, instead of carrying the whole job until the end. It's the standard approach on longer construction and remodeling jobs.

What is a 13-week cash flow forecast?

A week-by-week projection of cash in and out for the next quarter. It shows the lowest point your bank balance will hit, so you can act early by collecting, delaying purchases or lining up credit.