Flat-burn runway checkpoints

The checkpoints assume the same net burn repeats and ignore payment-day timing. In the default case, the reserve floor is crossed during month six even though cash remains positive. A weekly or 13-week forecast should govern near-term treasury decisions.

Cash-burn formulas

When inflows exceed outflows, net burn is zero for runway purposes and the business is cash-generative in this model. A negative mathematical burn is shown as net cash generation, while a finite runway is not reported.

Worked startup cash example

The business begins with $2.5 million of unrestricted cash and collects $450,000 during the month. It pays $350,000 for payroll, benefits, and payroll tax and $270,000 to vendors and other operating uses. Capex is $100,000, debt principal is $30,000, and one-time cash outflow is $50,000. Gross outflow is $800,000.

With no new financing, net burn is $350,000 and ending cash is $2.15 million. Operating receipts cover 56.25 percent of gross outflow. At unchanged burn, opening cash lasts 7.14 months to zero, but the $500,000 operating reserve is reached after 5.71 months. Treasury should act on the reserve runway, not celebrate the final theoretical month.

Prior burn was $300,000, so cash burn increased $50,000 or 16.67 percent. If net burn grows five percent each month, five full months remain before the reserve is breached. That stress case holds receipts and the composition of burn inside one growth rate; an operating forecast should model each line separately.

Gross burn, net burn, and runway answer different questions

Some teams define gross burn as only operating expenses and exclude capex, debt, or one-time items. This calculator includes every entered outflow so the cash bridge reconciles. Report a recurring operating burn separately if that view supports planning.

Why cash burn can differ sharply from net loss

Accrual accounting recognizes revenue when earned and expense when incurred under the applicable policy, not necessarily when cash moves. Accounts receivable can grow while reported revenue is strong. Paying old accounts payable can create cash burn without a new-period expense. Customer prepayments can provide cash before revenue recognition.

Depreciation reduces accounting profit without current cash payment. Capex uses cash but is generally capitalized and expensed over time. Debt principal reduces cash and a liability rather than current profit; interest has different treatment. Stock compensation, deferred revenue, inventory, taxes, and leases add further differences.

Build a reconciliation from operating result through working capital, noncash items, investing, and financing. Never forecast runway by multiplying reported loss when the cash conversion pattern is material.

Use unrestricted and available cash

Bank balance can include restricted deposits, customer funds, tax collections, escrow, compensating balances, trapped foreign cash, collateral, or amounts reserved for a specific obligation. Those balances may not fund payroll. The opening input should represent cash legally and operationally available for general use.

Undrawn credit is not cash. It can extend liquidity only if covenants, borrowing base, conditions, lender discretion, fees, and maturity permit. Show it in a separate liquidity scenario and include the repayment and interest consequences.

Reconcile bank accounts daily or weekly when runway is short. Include outstanding checks, ACH timing, card settlement, merchant reserves, payroll cutoffs, and fraud controls.

A reserve floor makes runway operational

Running to zero is not a workable plan. Businesses need cash for payroll, tax deposits, vendor minimums, refunds, insurance, debt covenants, regulatory capital, seasonality, and unexpected disruption. Set a reserve linked to obligations and risk, not a round number.

The default $500,000 reserve shortens useful runway from 7.14 to 5.71 months. Board and management triggers can sit above that floor: hiring freeze, discretionary-spend review, financing launch, restructuring, or strategic alternatives. Financing often takes longer than expected and can fail.

Review reserve after growth, acquisitions, payment-term changes, customer concentration, seasonal build, litigation, or macro stress. Preserve a downside cushion beyond the base forecast.

Replace one-month burn with a dated cash forecast

Averages hide payroll dates, annual insurance, quarterly tax, debt maturity, supplier deposits, renewals, inventory purchases, customer collections, and fundraising fees. Build a weekly forecast for the next 13 weeks and a monthly model beyond it. Start with opening bank cash and reconcile every period.

For receipts, model invoices, payment terms, historical collection curves, churn, refunds, processor delays, reserves, and concentration. For payments, use payroll registers, purchase orders, accounts payable due dates, leases, tax calendars, capex commitments, debt schedules, and contingencies.

Compare forecast with actual every week. Separate timing variance from permanent volume, price, hiring, cost, or collection changes. Update the runway rather than preserving a stale board-deck number.

Runway improvement has timing and consequence

Possible levers include faster billing, deposits, annual prepay, collections, inventory reduction, vendor terms, hiring pace, contractor cuts, marketing reallocation, facility changes, product pricing, capex deferral, asset sale, debt, equity, grants, and strategic partnerships. Each has operational, legal, customer, employee, and future-growth effects.

Do not count savings before cash timing changes. A headcount reduction can require notice, severance, benefits, legal review, and transition cost before lowering payroll. Canceling software can require a renewal date. Inventory commitments may be noncancelable.

Prioritize high-confidence, low-regret actions early. When the reserve runway is short, optimistic revenue growth without a committed pipeline is not a liquidity plan.

Liquidity metrics need definitions and controls

SEC MD&A rules and guidance emphasize material cash requirements, liquidity, and the drivers of financial condition for reporting companies. A private business also benefits from written burn definitions, source systems, reconciliations, owner review, and methodology history.

State whether financing counts as an inflow, whether capex and debt principal enter burn, which cash is excluded, what reserve applies, and whether the rate is one month, three-month average, or forecast. A one-time raise can make net burn look favorable without improving operations.

Use a trailing average to reduce noise, but retain the monthly bridge so a deteriorating trend is not hidden. Report both actual and forecast burn with variance explanations.

Tax cash deserves its own schedule

Payroll tax deposits, sales tax, estimated income tax, franchise tax, property tax, and tax settlements have distinct due dates and legal consequences. Collected trust-fund taxes should not be treated as available operating cash. The one-time input can capture a monthly amount but cannot calculate compliance.

IRS Publication 583 explains business records and separate business accounts.

Coordinate the cash forecast with qualified tax, payroll, legal, accounting, and treasury advisers. Preserve filing calendars, notices, deposit confirmations, payment plans, and restricted amounts.

Monthly cash runway checklist

1. Reconcile opening bank cash.
2. Exclude restricted balances.
3. Forecast customer collections by date.
4. Include payroll tax and benefits.
5. Map vendor payment due dates.
6. Separate capex from operating expense.
7. Include debt principal and interest.
8. Schedule taxes and one-time uses.
9. Set a defensible reserve floor.
10. Stress receipts and outflows separately.
11. Compare forecast with actual.
12. Start financing before urgency.

Frequently asked questions

References

• U.S. Small Business Administration, manage business finances and cash flow
• U.S. Securities and Exchange Commission, Form 10-K liquidity and capital-resources framework
• SEC guidance on management metrics and MD&A
• IRS Publication 583, Starting a Business and Keeping Records