--- title: "13-Week Cash Flow Forecast: Step-by-Step Guide | MCC" description: "Build a rolling 13-week forecast with a worked weekly example, update it with actuals, and spot a shortfall before it hits." url: "https://mcc-solutionsnj.com/bookkeeping/guides/13-week-cash-flow-forecast" --- Bookkeeping guide · Updated October 12, 2026 # How to Build a 13-Week Cash Flow Forecast Step by Step A 13-week cash flow forecast is a weekly projection of the money coming in and going out over the next quarter. It answers one question: will we have enough cash each week? It is practical, short-range and far more useful for survival than an annual plan. By [Matthew Coleman](/about), MCC Solutions **Quick answer.** A 13-week cash flow forecast is a weekly projection of cash in and out over the next quarter. Start with today's actual bank balances, build thirteen weekly columns, and let each week's closing cash become the next week's opening cash. Want this handled for you? Monthly bookkeeping, cleanup and year-end close for small businesses. Start with a free health check of your books. [Free health check](/bookkeeping/health-check)[Get a quote](/bookkeeping/#interest) **Related:** [NJ 1099 contractor rule (ABC test)](/bookkeeping/guides/nj-independent-contractor-rule-abc-test-2026) · [Trial balance explained](/bookkeeping/guides/trial-balance-explained) · [Owner contribution or loan](/bookkeeping/guides/owner-equity-and-capital-contributions) **Free tools:** [Bank reconciliation not matching?](/bookkeeping/bank-reconciliation-difference-finder) · [Are my books ready for taxes?](/bookkeeping/is-my-quickbooks-ready-for-taxes) [![Intuit ProAdvisor Gold tier badge](/img/credentials/intuit-proadvisor-gold.png)](https://proadvisor.intuit.com/app/accountant/search?searchId=matthew-coleman77)Gold tier in Intuit's ProAdvisor program. [See my Intuit listing](https://proadvisor.intuit.com/app/accountant/search?searchId=matthew-coleman77) Keeping your own books? Tallyfinch does invoices, bank import and reports on your computer. [See Tallyfinch](/bookkeeping/mcc-books-downloadable-bookkeeping-software) ## Step 1: Start with real cash Begin with the actual balance in every bank account as of today, not the figure from your last report. Use a spreadsheet with thirteen columns, one per week, and rows for opening cash, cash in, cash out and closing cash. Each week's closing balance becomes the next week's opening balance. This is where reconciled books matter. If your records are behind, you may not know what has actually cleared the bank, and the starting point is already wrong. ## Step 2: Forecast cash in by timing List expected receipts by week. For invoiced customers, pull the open receivables report from QuickBooks Online or Xero and estimate when each will really pay, based on how that customer has paid before, not the due date. For retail or card sales, use recent weekly patterns and remember that processors often deposit a day or more later and net of fees. Be conservative. If a large customer usually pays two weeks late, plan for two weeks late. Count only sales you have good reason to expect. ## Step 3: Forecast cash out by obligation List fixed items first: payroll, rent, loan payments, insurance, software subscriptions and utilities. Then add variable costs such as inventory and materials, using the open bills report to see what is due and when. Add periodic items that are easy to forget, such as quarterly tax payments, annual insurance premiums and equipment purchases. Ask your CPA what payments to plan for, since tax timing is their area. Include owner draws or distributions explicitly. Leaving them out is a common reason forecasts look healthier than reality. ## Step 4: Find the low point Look at the closing balance each week and mark the lowest one. That is your pinch point. Decide in advance what you will do if the balance dips below a minimum you set. Options include chasing invoices, delaying a purchase, negotiating a vendor payment date or arranging a credit line before you need it. Seeing a shortfall six weeks ahead gives you choices. Seeing it six days ahead usually gives you only expensive ones. ## Common pitfalls The most frequent error is treating the forecast as a one-time exercise. Another is mixing accrual thinking with cash thinking: a sale you invoiced is not cash until it is collected, and a bill you received is not cash out until you pay it. Keep the model strictly on dates money moves. A third is ignoring seasonality, so check the same weeks last year for patterns before you project this quarter. Finally, keep a short list of assumptions beside the sheet. When the forecast misses, the list tells you which assumption failed. ## Step 5: Update weekly Roll the forecast forward each week. Replace last week's estimates with actuals, add a new thirteenth week and note why any big variance happened. Over a few months you will learn where your estimates run optimistic, and the forecast gets sharper. A short weekly review of fifteen minutes is enough. If maintaining it feels like too much, MCC Solutions can build and update one from your monthly books as part of its planning support. ## Worked example with numbers Opening cash is $18,000. Week 1 expects $9,000 of collections and $11,500 of payments (payroll $6,000, rent $2,500, vendors $3,000). Ending cash is $18,000 + $9,000 - $11,500 = $15,500. Week 2 expects $4,000 in and $3,200 out, ending at $16,300. Keep rolling forward. If any week falls below your minimum cash cushion, you can see it three months ahead and act, by collecting sooner or timing a large payment. ## Check your work Each week, replace the forecast with actuals and note why they differed. Patterns show which assumptions are weak. ## Common questions **Why thirteen weeks and not twelve months?** Thirteen weeks is one quarter. It is short enough to estimate with reasonable accuracy and long enough to spot problems while you still have time to act. **Can I build it in QuickBooks Online or Xero?** The software supplies the inputs, such as receivables, payables and bank balances. Most owners build the forecast in a spreadsheet using those reports. **How accurate does it need to be?** It needs to be useful, not perfect. Track the gap between forecast and actual each week and adjust your assumptions. This guide is general information, not tax, legal or accounting advice. Rules, fees and due dates change; check with the IRS, the NJ Division of Taxation or a licensed professional for your situation. Let us handle it [### Monthly bookkeeping Categorizing, reconciling and monthly reports, with cleanup, payroll and NJ filings available. Bookkeeping →](/bookkeeping/) [### QuickBooks Online Monthly bookkeeping, cleanup and reconciliation in QuickBooks Online for New Jersey small businesses. Your account stays in your name. QuickBooks →](/bookkeeping/software/quickbooks-online)[### Xero Bookkeeping and reconciliation in Xero for New Jersey small businesses, including cleanup and moving from spreadsheets or another program. Xero →](/bookkeeping/software/xero) More guides - [How to Prepare a Lender-Ready Financial Package](/bookkeeping/guides/lender-ready-financial-package) - [KPI Dashboard for Small Business Owners: What to Track](/bookkeeping/guides/kpi-dashboard-for-small-business-owners) - [Budget vs Actual: How to Run a Monthly Review Meeting](/bookkeeping/guides/budget-vs-actual-monthly-review) - [Pricing and Margin Analysis for a Small Business](/bookkeeping/guides/pricing-and-margin-analysis-for-small-business) Free tool - [Bookkeeping health check](/bookkeeping/health-check) [All guides](/bookkeeping/guides) Reach small business owners, freelancers and bookkeepers who read this guide: [advertise here](/advertise#bookkeeping). ## Try a quick 13-week cash flow Enter a few numbers to see 13 weeks of cash and your lowest week. It is deliberately simple: sales come in the same each week (or grow by a percent you set), payroll goes out every other week, and rent and a loan payment go out every fourth week. Nothing is sent or saved. A rough guide. It ignores when customers actually pay you, taxes due on set dates and surprises. The [13-Week Cash Flow Forecast workbook](/toolkits/cash-flow-forecast-13-week) spreads customer payments over the weeks they usually arrive, puts monthly and quarterly bills in the week they fall due, and adds a stress case. Not financial advice. Excel workbook ### 13-Week Cash Flow Forecast List what you expect to collect and pay, and see your cash balance each week, the lowest point and when it happens. [See what is inside ($29)](/toolkits/cash-flow-forecast-13-week) [Try the free starter](/toolkits/cash-flow-forecast-13-week#free-starter) Also in the [Business Planning Bundle](/toolkits/business-planning-bundle): 4 products for $79 instead of $106 separately. Tallyfinch ### Books you keep on your own computer Tallyfinch does invoices, bills, bank import, reconciliation and the main reports, in a file you own. $99 once, then $5 a month for updates; the app keeps working if you stop the plan. It does not do payroll or sales tax filing. The free download records up to 60 entries. [See Tallyfinch](/bookkeeping/mcc-books-downloadable-bookkeeping-software) [Download it free](/tools/pro/trial/mccBooks) [Compare the three apps](/software) ## Rather have us keep the books? Ask for a quote. [Get a Quote](/bookkeeping/#interest)[Call (908) 444-6373](tel:+19084446373)