How to Build a 13-Week Cash Flow Forecast (Free Google Sheets Template)

A 13-week cash-flow forecast helps a small-business owner see whether a payroll run, supplier payment or delayed customer invoice will leave too little cash in a particular week. It follows actual expected receipts and payments rather than relying on a month-end profit figure. The important result is the lowest projected cash balance and the action you can take before that week arrives.

Start with the free 13-week cash-flow workbook (Google Sheets model). It includes an editable 13-week forecast, a four-week check, a chosen cash floor, a reserve-planning tab and a scenario that moves one expected receipt to a later week. The figures are fictional; replace them before making a real decision.

Gather the four inputs that make the forecast useful

Workbook formats: download the Excel forecast (XLSX) or make a copy in Google Sheets. The cash-flow management guide explains the weekly decisions that follow from these numbers.

Opening cash: Start with the actual available balance of your business bank accounts, adjusted for uncleared checks, outstanding payments or funds you cannot spend. Confirm the date of the balance. A customer invoice or an approved but undrawn loan is not cash you have today.

Likely receipts: List cash that you reasonably expect to clear during each week. An overdue invoice with an unresolved dispute is less dependable than a recurring client payment with a confirmed date. Keep a note of the assumption and revisit it at each weekly review.

Dated payments: Gather payroll, employer taxes, rent, supplier commitments, loans, insurance, equipment and discretionary payments. Use actual contractual or legally required dates; do not move required payments into convenient weeks just to make the forecast look better. Ask your payroll contact or accountant to verify tax timing.

Chosen operating floor: Select the minimum balance at which you want to review spending and collections. It is an owner planning assumption informed by essential bills and collection risk. It is not a universal rule or automatically the amount you should borrow.

Set up the first forecast week

Open the workbook’s 13-Week Forecast tab. Set the first week to the Monday that begins your forecasting period, enter your opening available cash and set the cash-floor assumption. The 13 week-start dates then extend from that start date in seven-day intervals.

Enter receipts as positive amounts under customer cash collected, other cash received and financing actually drawn. If funding has not reached the bank, leave it out until you have a defensible assumption for its arrival. Enter payments as positive amounts under their categories. The formulas subtract cash payments, so entering them as negative numbers would misstate the forecast.

Keep categories clear. Wages and employer taxes appear in separate rows. Supplier or material payments should reflect when funds leave the account, even if the expense was recorded in an earlier accounting period. A customer deposit may increase available cash before all the work needed to earn it has been done. Include the future costs of serving that customer, too.

Link opening and closing cash across 13 weeks

The core formulas are simple: Total cash in = sum of incoming cash rows; total cash out = sum of outgoing cash rows; net movement = cash in minus cash out; closing cash = opening cash plus net movement. Week two opens with week one’s closing cash, and the same relationship repeats through week 13.

The workbook calculates a weekly shortfall against your chosen cash floor. Until the required payment dates in row 30 and the inflow/outflow assumptions in row 31 are both marked REVIEWED, its status reads VERIFY INPUTS. Only then does the status say BELOW FLOOR or OK. A zero in week five or beyond is an unreviewed placeholder in the fictional model, and could hide an actual upcoming payment. A cash floor is a planning trigger, so also inspect upcoming obligations within a week, especially payroll and any deposits that can clear after a due date.

Check a four-week fictional example

Northgate Property Services, a fictional commercial cleaning company, begins with $18,000 available cash. It expects $11,000 in week one, $9,000 in week two, $2,000 in week three, and $15,000 in week four after a customer payment moves later. Payroll lands in weeks one and three.

The example closes week four at $8,500, but the low point is just $500 in week three. If the owner selected an $8,000 operating floor, that week is $7,500 below the floor. The business hasn’t necessarily missed a bill in the forecast; the remaining balance has become too thin for comfort. The owner should investigate the receipt delay and realistic payment options before the risky week arrives.

This case is a planning demonstration, not observed company data. The workbook’s first four weeks contain those exact figures; you can inspect each incoming and outgoing amount in the underlying rows.

Test a delayed customer payment

Open the Delay Scenario tab. Choose a source week, an amount already included in that week’s receipts, and the destination week. The scenario removes the amount from the source week, adds it to the later week, and recalculates closing cash. The destination must be later than the source, and the shifted amount must be positive and no greater than that week’s customer cash collected amount. An invalid week selection displays INVALID INPUT; an excessive payment amount displays EXCEEDS CUSTOMER RECEIPTS.

For a meaningful stress test, consider the large customer you cannot afford to have pay late. If that customer is expected to send $9,000 in week four, moving it to week five should make the week-four closing cash $9,000 lower than in the base case, before considering any later changes. If that produces a negative balance, look for the first actual obligation that cannot be met.

Moving a receipt changes timing, not whether the customer ultimately pays. If the invoice could be partly uncollectible, create a separate conservative forecast or remove the uncertain portion instead of assuming all delayed money eventually arrives.

Check reserve coverage and a monthly view without confusing the tasks

The Reserve Target tab multiplies the essential weekly outflow you enter by your chosen weeks of coverage, then adds a one-time risk allowance. The sample uses $8,500, two weeks and $5,000, resulting in a fictional $22,000 target. Revisit the assumptions for your actual business; no universal reserve target is implied.

The 12-Month Planning tab is a separate high-level sketch. It starts without receipt or payment forecasts. Closing cash stays blank until you provide both monthly inputs. The monthly view cannot replace dated 13-week checks when payroll or supplier payments create a short-term cash squeeze.

Update the forecast every week

A genuine rolling forecast replaces the week that just finished with a new future week while retaining an accurate record of what really happened. The workbook contains a Weekly Closeout tab for this purpose. It includes a clearly labeled fictional example and blank rows for your own weekly variance checks.

1. Close the completed week. Before overwriting anything, copy the prior forecast closing amount from the finished week to Weekly Closeout. Enter actual opening bank cash, cleared receipts, cash payments and the reconciled bank balance. Check both forecast variance and any bank reconciliation difference.
2. Move forecast input values only. On 13-Week Forecast, copy D10:O12 and paste values into C10:N12. Repeat for payment input rows D15:O22 into C15:N22. Leave formula rows untouched. The first week is now the former second week.
3. Update the starting point. Advance B3 by seven days. Replace B5 with the verified available bank balance at the start of the new week. Enter anticipated cash in and out for the newly added thirteenth week in column O.
4. Reset checks and review. Set every week in rows 30 and 31 to ACTION REQUIRED. Recheck due dates, payroll, taxes, customer receipts and unknowns. Mark each REVIEWED only after you have checked the obligations and cash assumptions. Then inspect the new lowest cash balance.

Do not copy or move formulas when shifting forecast inputs. If a bank reconciliation difference remains unexplained, correct the actuals rather than forcing the forecast to match. A weekly forecast also cannot show a cash shortage that occurs inside the week before a Friday receipt, so separately check sensitive payroll and tax cutoffs.

The Google Sheets workbook contains a forecast, four-week summary, reserve estimate, delayed-receipt test, monthly planning sheet and weekly closeout record. All 13 weeks require explicit due-date and forecast-input checks. Its formulas recalculate in Google Sheets. It does not include bank feeds, automated due-date verification, tax advice or an alert service. For a shorter owner’s routine, see How to Manage Cash Flow in a Small Business. The IRS’s Employer’s Tax Guide covers federal employer tax obligations that require their own timing checks.