How to Build a 13 Week Cash Flow Forecast

A 13 week cash flow forecast shows when money is expected to enter and leave your bank account each week.

It does not replace the income statement. It answers a different question.

Will the business have enough cash to meet payroll, vendors, debt, taxes, and planned spending on time?

Unlock the free 13 week cash flow forecast template and use the steps below to replace the example inputs with your business information.

What a 13 Week Cash Flow Forecast Shows

The forecast begins with available cash. It then adds expected receipts and subtracts expected payments for each of the next 13 weeks.

The basic formula is:

Beginning cash + cash receipts - cash disbursements = ending cash

Each week’s ending cash becomes the next week’s beginning cash.

The model gives management a short enough time frame for detailed estimates and enough time to respond to a problem. Thirteen weeks also covers a full quarter, including payroll cycles, monthly debt payments, vendor terms, and many tax dates.

Profit and Cash Are Different

A profitable business still runs short of cash.

Revenue appears on the income statement when earned. Cash arrives when the customer pays. Expenses appear when incurred. Cash leaves when the bill clears the bank.

Timing creates the gap.

Common causes include:

• Customers paying later than expected
• Inventory or materials purchased before the related sale
• Payroll due before a project billing clears
• Loan principal payments excluded from the income statement
• Owner distributions
• Tax payments
• Capital spending
• Retainage and progress billing delays

The forecast tracks the bank timing behind those items.

Start With Available Cash

Use unrestricted cash expected to be available at the start of Week 1.

Include operating checking and other accounts available for normal business use. Exclude restricted funds unless the planned use meets the restriction.

Reconcile the amount to the bank. Do not begin with a balance pulled from an unreconciled general ledger.

If checks or automatic payments have been issued but have not cleared, account for them once. Either reduce beginning cash or include the payments in Week 1. Do not do both.

Build the Cash Receipts Forecast

Start with customer collections because they often drive the largest forecast risk.

For large invoices, forecast by customer and invoice. Use the date cash is expected to clear.

Review:

• Invoice due date
• Customer payment history
• Open disputes
• Required approval steps
• Scheduled ACH or card settlements
• Project milestones
• Retainage
• Expected deposits

Do not move every invoice into the week shown by its payment terms. Use observed customer behavior.

Group smaller, predictable receipts when invoice detail adds little value. Keep large or uncertain collections visible.

Add other receipts only when management has a reasonable basis for the timing. Examples include cash sales, tax refunds, loan proceeds, asset sales, and owner contributions.

Map Cash Disbursements by Payment Date

Build the payment schedule from known commitments first.

Start with:

• Payroll
• Payroll taxes and benefits
• Inventory and materials
• Subcontractors
• Rent and occupancy
• Debt service
• Income, sales, and property taxes
• Insurance
• Software and professional fees
• Capital expenditures
• Owner draws and distributions

Use actual payroll dates, debt payment dates, tax due dates, and vendor commitments.

Review recent bank activity for costs missed by the general ledger categories. Annual subscriptions, quarterly insurance, equipment deposits, and tax payments often create surprise weeks.

Separate committed payments from discretionary spending. When a gap appears, management needs to know which payments have timing flexibility.

Set a Minimum Cash Target

Ending cash above zero is not always enough.

Set a minimum cash target based on the amount needed to absorb normal uncertainty. Consider payroll, debt covenants, vendor commitments, customer concentration, seasonality, and access to a line of credit.

The target should reflect the business. A company with predictable subscriptions and low fixed costs needs a different reserve from a contractor funding labor and materials before collection.

The template compares projected ending cash with the target each week. A negative gap deserves an owner and an action date.

Calculate Each Week

For Week 1:

1. Enter beginning cash.
2. Add expected cash receipts.
3. Subtract expected cash disbursements.
4. Calculate ending cash.
5. Compare ending cash with the minimum target.

For Week 2, link beginning cash to Week 1 ending cash. Repeat the process through Week 13.

Keep formulas separate from inputs. In the downloadable workbook, blue cells are inputs. Gray and navy rows contain formulas.

Review the Cash Low Point

The final week is not the only result to review.

A forecast might end with a healthy balance and still show a serious gap in Week 4.

Review:

• Lowest projected cash balance
• Date of the low point
• Weeks below the minimum target
• Largest expected receipt
• Largest expected payment
• Customer concentration in receipts
• Payments with timing flexibility

The Dashboard in the template shows the low point and the weeks below target.

Run a Weekly Forecast Routine

Update the forecast on the same day each week.

Use this routine:

1. Reconcile current cash.
2. Replace the prior week estimate with actual cash activity.
3. Explain material differences.
4. Update collection dates with current customer information.
5. Update payment dates with current commitments.
6. Add a new Week 13.
7. Assign actions for every cash gap.

The forecast becomes more useful when management records why estimates changed.

A delayed receipt might signal a collection problem. Higher material spending might signal growth, weak purchasing control, or an estimate error. The cash difference alone does not explain the business issue.

Compare Forecast With Actual Cash

Forecast accuracy improves through variance review.

For each large difference, ask:

• Did the amount change?
• Did the timing change?
• Was the item omitted?
• Was the assumption too optimistic?
• Did an operational decision change the result?

Track repeated misses. If customers consistently pay two weeks later than forecast, update the collection assumption. If payroll taxes keep appearing as surprises, add them to the standard payment schedule.

The goal is not perfect prediction. The goal is earlier notice and better decisions.

Test the Downside

After the base forecast is complete, test pressure points.

Move uncertain receipts later. Move uncertain costs earlier. Add a realistic sales slowdown. Include a delayed project, lost customer, equipment repair, or tax payment under review.

Then identify the first week below the cash target.

Management responses might include:

• Accelerating collections
• Requesting customer deposits
• Changing purchase timing
• Delaying discretionary spending
• Renegotiating vendor terms
• Using an approved credit line
• Adjusting owner distributions
• Revising hiring or capital plans

Decide before the gap arrives.

Avoid Common Forecast Errors

Several errors reduce trust in the model:

• Using profit instead of bank timing
• Forecasting every customer at stated terms
• Ignoring payroll taxes and benefits
• Omitting loan principal
• Leaving tax payments out
• Counting a receipt twice
• Treating restricted cash as available
• Updating the forecast only during a crisis
• Hiding uncertain items inside one large category
• Failing to assign actions

A simple model with named assumptions is more useful than a detailed model no one updates.

Use the Forecast in Management Meetings

Place the cash forecast beside the income statement and balance sheet.

The income statement shows operating performance. The balance sheet shows resources and obligations. The cash forecast shows timing.

Together, they support decisions about collections, purchasing, hiring, pricing, capital spending, debt, and owner distributions.

For a business with job, location, or customer concentration, add supporting schedules outside the main forecast. Keep the 13 week view readable.

Download the 13 Week Cash Flow Forecast Template

Use the short form below to unlock the Kruse & Crawford 13 week cash flow forecast template.

The Excel workbook includes:

• A Start Here guide
• Editable assumptions
• A 13 week forecast with example inputs
• A cash low point Dashboard
• A minimum cash target
• Formula checks

Replace the blue example inputs before using the results for a decision.

A qualified accounting advisor should be consulted when the forecast depends on financing limits, tax obligations, restricted cash, or complex operating assumptions.