13-week cash flow forecast: how it works
A 13-week cash flow forecast shows when money is expected to enter and leave your business, week by week. It turns near-term cash timing into a rolling decision view—not a promise of what your bank balance will be.
The method in one formula
Weekly ending cash = beginning cash + receipts − disbursements.
Carry each week's ending cash into the next week's beginning cash. Keep thirteen weeks visible: after recording the completed week's actuals, add a new week at the end. Use a cash view rather than assuming revenue is collected or an expense is paid when it appears in your profit and loss statement.
What to include
- Beginning cash: available balances in the bank accounts included in the forecast. Identify restricted cash separately.
- Receipts by source: customer collections, deposits, and other expected inflows, placed in the week cash is expected to arrive. Treat uncertain funding as a separate assumption.
- Disbursements by category: supplier payments, payroll totals, rent, loan payments, owner distributions, and other cash commitments in their expected payment weeks.
- Tax payments: include expected cash dates and amounts supplied by your CPA; do not use the forecast to determine tax treatment.
- Net cash flow and ending cash: show receipts minus disbursements, then the resulting weekly balance.
- Minimum cash threshold: an owner-approved operating buffer against which to review the forecast, not a universal benchmark.
Who needs a 13-week forecast?
It can be useful when collections are uneven, payroll and supplier dates do not align with receipts, seasonal demand changes cash needs, or a hiring or growth decision is approaching. Startups can use it alongside a longer runway model; established businesses can use it alongside budgets and monthly reporting.
The thirteen-week view focuses on near-term payment timing. It complements, rather than replaces, a longer-range forecast and reconciled books.
A weekly owner workflow
- Confirm actual opening and closing cash against bank activity.
- Replace the completed week's forecast with actual receipts and payments.
- Compare actuals with the prior forecast; separate timing shifts from changes in amount.
- Refresh open receivables, payment commitments, and assumptions with the people responsible.
- Roll the model forward one week and review balances against the operating buffer.
- Record decisions, owners, and the next review date.
Test a downside case before deciding
Keep the base case and downside case separate. For example, move a significant customer receipt to a later week or reduce an uncertain inflow. Review which weeks cross the operating buffer and which actions remain available.
Use the result to discuss collections follow-up, timing of discretionary spending, or a lender conversation. Document authorized decisions; the forecast does not authorize bill payment, borrowing, or moving money between entities.
Common mistakes to avoid
The Aligned Ledger provides cash flow forecasting and advisory for management use. We are not a CPA firm and do not provide tax preparation, payroll processing, bill pay, or attest/assurance services. Talk to your CPA about tax assumptions and your attorney about legal obligations.
- Using invoice dates instead of expected cash receipt dates.
- Treating hoped-for funding as committed cash.
- Counting transfers between included bank accounts as new receipts.
- Combining entity balances without distinguishing ownership and availability.
- Leaving assumptions unchanged after actual cash moves.
- Showing precision without documenting uncertainty or assigning an input owner.
Frequently asked questions
What is a 13-week cash flow forecast?
It is a rolling weekly view of expected cash receipts, disbursements, and ending balances over thirteen weeks. It supports near-term decisions about cash timing and commitments.
How do you calculate weekly ending cash?
Beginning cash plus receipts minus disbursements equals ending cash. That ending balance becomes the following week's beginning balance.
How often should the forecast be updated?
Review it weekly: replace the completed week's forecast with actuals, reconcile to cash activity, explain differences, refresh assumptions, and add the next week. Revisit material changes sooner when needed.
Is this the same as a budget?
No. A budget sets a financial plan, while the 13-week forecast concentrates on when cash enters and leaves. Revenue and expenses do not necessarily occur in the same weeks as collections and payments.
Can The Aligned Ledger help build the forecast?
Yes. Cash flow forecasting and scenario planning are part of our advisory scope. Book a call to discuss your records, cash commitments, and the decisions you need to evaluate. Tax assumptions should be reviewed with your CPA.
Connect the record to the next decision
Talk with us about your reporting, cash timing, and the decisions ahead.
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