13-Week Cash Flow Forecast for Contractors: Plan Ahead for Payroll

Your bank balance shows what is available now. It does not show whether next month’s payroll, supplier bills, and equipment payments will arrive before your customers’ money.

That is the question a 13-week cash flow forecast for contractors should answer.

Rather than predicting annual sales, this weekly forecast tracks expected receipts, scheduled payments, and the cash remaining after both. It gives construction, trades, and service-business owners a practical way to identify timing gaps before making another spending commitment.

What Is a 13-Week Cash Flow Forecast?

It is a rolling projection covering the next 13 weeks. Each week, replace the completed week’s estimates with actual results, investigate differences, and add another week to the end.

BDC recommends this weekly approach for closer visibility than a monthly cash budget provides.

Keep it separate from your profit report. Work can generate accounting profit before the customer pays; cash availability depends on collections and payment timing.

Use both reports. A cash forecast helps answer whether bills can be paid. Job costing helps answer whether the work is worth doing.

1. Start With Cash You Can Actually Use

Choose a consistent weekly cutoff and reconcile the starting cash balance with your bookkeeper.

Identify outstanding checks and scheduled withdrawals. Either reflect them in the opening balance or show them as upcoming payments—not both.

Keep restricted funds separate from cash available for general operations. An undrawn credit line is not cash already in the bank.

For your first version, create 13 weekly columns and rows for opening cash, customer collections, other receipts, payments, and ending cash.

Ending cash = Opening cash + Cash received − Cash paid

Carry each week’s ending balance into the following week’s opening balance.

2. Forecast Customer Payments, Not Just Invoice Dates

For each significant receivable, record the expected amount, likely payment week, and person responsible for checking its status.

Use customer payment history, billing approval status, and current conversations to support the date. RSM emphasizes realistic, achievable assumptions when projecting receipts and payments.

An invoice due Friday is not necessarily money available for Friday’s payroll.

Include expected deposits and progress payments when supported by the job agreement and a realistic collection date. Keep uncertain proposals separate from committed work; do not depend on winning an unaccepted estimate to make the forecast balance.

For projects with retainage, separate the amount withheld from the payment expected now. Retainage is a portion held until specified project conditions are met.

Do not assume it will arrive at ordinary invoice due dates.

3. Put Payments in the Weeks They Leave the Bank

Use actual due dates and project schedules rather than spreading every cost evenly across the month.

Include payroll, tax remittances, materials, subcontractors, equipment, rent, insurance, software, debt payments, and planned owner distributions.

Add approved purchases that have not yet become supplier invoices. Ask project managers what upcoming work requires, not only what accounting has already recorded.

Keep loan proceeds and repayments separate from customer collections and operating payments. Borrowing can change cash availability without improving the job’s profitability.

Avoid double-counting credit-card purchases and the later card payment. This forecast tracks cash movement; have your bookkeeper confirm the treatment of transactions already recorded elsewhere.

4. Look for the Lowest Balance, Not Just the Final Balance

Consider this hypothetical four-week excerpt from a 13-week forecast. It assumes no additional financing.

Over four weeks, the company expects $95,000 in receipts and $120,000 in payments. With $45,000 of starting cash, the period ends at $20,000.

But week three has a projected $5,000 funding gap.

The negative balance represents payments the business cannot fully fund under these assumptions—not permission to overdraw an account. It carries forward here only to show the unresolved gap.

These are illustrative figures, not a GTI client result.

Also review payment order within a week. Friday’s customer receipt cannot fund Tuesday’s payroll. When cash is tight, expand the near-term forecast into daily detail.

5. Test One Delayed Payment Before It Happens

Create a second version in which a named customer payment arrives later.

For example, move $10,000 of the expected week-two receipts to week four, leaving everything else unchanged. Week three’s projected shortfall increases from $5,000 to $15,000, even though the four-week ending balance stays the same.

That is a timing problem a period-end total can conceal.

Next, identify actions rather than changing assumptions to make the numbers look better. Check whether billing documentation is missing, confirm payment status, or reconsider an uncommitted purchase.

Discuss any proposed payment changes with the affected party and honor contractual and legal obligations. Do not silently postpone payroll, taxes, or supplier commitments in the model.

If financing may be needed, discuss it with your financial adviser and lender before the projected shortfall. Approval and available borrowing capacity should never be assumed.

6. Turn the Forecast Into a Weekly Decision Meeting

Assign one person to maintain the forecast, with input from accounting, operations, and the owner.

Review three questions:

• Which receipt or payment changed most?

• What is the lowest projected cash balance, and when does it occur?

• What action must someone complete before that date?

Set an operating cushion appropriate to your obligations and uncertainty. Treat a forecast below that cushion as a review trigger, even when the balance remains positive.

Keep last week’s forecast so the team can compare predictions with actual cash movement. BDC recommends reviewing actual results against projections and adjusting plans when differences emerge.

The purpose is not a perfect spreadsheet. It is better assumptions and earlier decisions.

Make Cash Planning Part of Running the Business

Start with current bank balances, open receivables, bills due, payroll dates, and committed project spending. Build the first version with your bookkeeper, then update it consistently.

A weekly cash flow forecast does not fix underpricing or make an unprofitable job profitable. It makes the timing of financial commitments easier to see.

GTI Consulting LLC helps owners evaluate upcoming cash needs, compare forecasts with actual results, and connect financial information to operating decisions alongside their existing accounting professionals.

Contact GTI Consulting to discuss a Profitability & Operations Review. Bring your receivables list, payroll schedule, upcoming bills, and active-job commitments so the conversation starts with specific cash pressures—not guesswork.