The short answer: Runway scenario planning models three cases before cash gets tight: base, downside, and extension. Each one needs its own zero-cash date and a written trigger. In the worked example below, $3,600,000 of cash lasts 19.3 months in the base case, 16.0 months in the downside case, and 30.0 months once extension actions are added.
- Flat collections cost this company 3.3 months of runway against a plan of 2% monthly growth.
- A $96,000 monthly cost cut adds 8.2 months if it starts in month 5.
- Each month of delay removes about 0.74 months of that gain.
- Set the trigger while the runway still covers the full response time.
Last updated November 2026.
A single runway number assumes the plan holds. Three cases show what happens when it does not, and how much time management has to respond. The value of the exercise sits in the decisions it dates, since nobody can forecast month 16 with precision.
This guide builds runway scenario planning line by line for one illustrative company. If the underlying inputs still need work, start with how to calculate burn rate and runway. The 13-week view handles near-term liquidity; these cases cover the 12–30 months beyond it.
What runway scenarios should every startup model?
Every startup should model a base case, a downside case, and an extension case. The first two describe what could happen to the business. The third describes what management would do about it.
- Base case. The current operating plan, tied to the latest closed month.
- Downside case. The one or two assumptions most likely to miss, with no response from management. Changing everything at once hides the cause.
- Extension case. The downside case plus dated actions: cost cuts, bridge financing, or changed billing terms.
Keep the downside free of fixes. Mixing the two makes the risk look smaller than it is and leaves the board unable to see what each action buys.
How does runway scenario planning work in a worked example?
Take an illustrative seed-stage company at the start of month 1. It holds $3,600,000 of cash, spends $412,000 a month, and collects $187,000 a month. Net burn starts at $225,000 a month.
- Base case. Collections grow 2% a month, and spending stays flat. Net burn falls to $139,576 by the final month, and cash runs out in month 19.3 of the plan.
- Downside case. Collections stay flat at $187,000. The arithmetic is simple: $3,600,000 ÷ $225,000 = 16.0 months.
- Cost action. A $96,000 monthly cut starts in month 5, with $96,000 of one-time severance that month. Cash at the end of month 5 is $2,700,000 − $225,000 = $2,475,000. New net burn is $129,000, and $2,475,000 ÷ $129,000 = 19.2 further months, which lands on month 24.2.
- Bridge. A $750,000 note funds in month 9. Then $750,000 ÷ $129,000 = 5.8 more months, which lands on month 30.0.
How does the zero-cash date move under each case?
The zero-cash date moves with the assumption changed and the month the change takes effect. The table shows all three cases side by side, which is the form a board can act on.
| Case | Collections | Actions | Cash, end of month 12 | Zero-cash month |
|---|---|---|---|---|
| Base | +2% a month | None | $1,164,061 | 19.3 |
| Downside | Flat | None | $900,000 | 16.0 |
| Downside + cost cut | Flat | $96,000/mo from month 5 | $1,572,000 | 24.2 |
| Extension | Flat | Cost cut + $750,000 bridge in month 9 | $2,322,000 | 30.0 |
The bridge alone, with no cost cut, reaches only month 19.3 in the downside case: $750,000 buys 3.3 months at $225,000 of net burn. After the cut, the same money buys 5.8 months. Sequence matters as much as size.
What triggers moving to the downside plan?
A trigger is a written metric, threshold, and duration, agreed before anyone needs it. Without one, the decision tends to wait for a bad month that cannot be explained away.
In this example, base-case collections reach $194,555 in month 3 and $198,446 in month 4. Flat collections of $187,000 fall 3.9% and 5.8% short. A rule of “3% or more below plan for two closed months” therefore fires after month 4 closes, which is how the cut lands in month 5.
Test the rule against response time. If raising a bridge would take an assumed 6 months and the board wants a 3-month cushion, the plan must act while at least 9 months remain. Under the downside case, that deadline is the end of month 7.
What does waiting cost once the trigger fires?
Waiting has a measurable price. Each month of delay here costs about 0.74 months of runway, because the $96,000 saving is lost while net burn after the cut is $129,000: $96,000 ÷ $129,000 = 0.74.
| Cut starts in | Cash, prior month-end | Zero-cash month | Runway lost to delay |
|---|---|---|---|
| Month 5 | $2,700,000 | 24.2 | None |
| Month 7 | $2,250,000 | 22.7 | 1.5 months |
| Month 9 | $1,800,000 | 21.2 | 3.0 months |
| Month 11 | $1,350,000 | 19.7 | 4.5 months |
Legal notice can add lag. The federal WARN Act says: “An employer shall not order a plant closing or mass layoff until the end of a 60-day period after the employer serves written notice of such an order.” It generally reaches employers with 100 or more employees, excluding part-time staff, and its triggering thresholds apply separately. A covered company that pays staff through the notice period should start the saving about 2 months later in the model. Counsel should confirm coverage, including any state rules.
How do you model a runway extension or bridge?
Model each extension action as a dated cash event, then add its terms. A bridge appears as one inflow, but it also brings interest, a maturity date, and dilution.
Assume the $750,000 note carries 8% simple interest and converts at an $8,000,000 pre-money valuation. Interest accrues at $60,000 a year. If the note converts with no payment of interest in cash, it adds no monthly burn. Before interest and any new-round shares, conversion comes to $750,000 ÷ $8,750,000 = 8.6% of the company. Those terms are illustrative. For reference, the Federal Reserve’s H.15 release showed a 7.00% bank prime rate on October 29, 2026.
Mark a note that may be repaid in cash at maturity on the timeline, because repayment would reverse the extension. Tie larger spending decisions to the proof points in a milestone-based budget.
Why does the 12-month line matter for GAAP statements?
Companies that prepare GAAP financial statements face a one-year test, so downside runway can matter before cash is short. FASB ASU 2014-15 sets the standard. Substantial doubt exists when “it is probable that the entity will be unable to meet its obligations as they become due within one year after the date that the financial statements are issued (or available to be issued).”
The window runs from issuance, and the balance sheet date comes earlier. Suppose statements for month 12 are issued in month 16. The test then runs through month 28, which is later than the zero-cash month in the first three rows of the table. Lenders and investors may ask for that analysis, so have the scenario file ready before audit fieldwork begins. Management and its auditor make the actual conclusion, and it depends on the facts at issuance.
How often should scenarios be refreshed?
Refresh all three cases monthly, immediately after the close. Actuals replace forecast months, and the trigger metrics are tested against closed numbers. Stale books produce a stale zero-cash date, which is why the close comes before the model.
The Continuous Close Method™ at Debit & Co. supports this rhythm, and Aaron Ressel and Kevin Cahill review the close packet before it ships. Report the results alongside the rest of the burn and runway page for the board, with one line for each zero-cash date and any trigger that fired.
Frequently asked questions
What runway scenarios should every startup model?
Three: a base case built on the current plan, a downside case in which the main revenue or funding assumption misses, and an extension case that adds the specific actions management would take in response. In the worked example, those cases put the zero-cash date at month 19.3, month 16.0, and month 30.0.
What triggers moving to the downside plan?
A written metric, threshold, and duration agreed in advance. One workable form: collections 3% or more below the base case for two consecutive closed months. The trigger should fire with enough runway left to complete the response, including any fundraising lead time.
How do you model a runway extension or bridge?
Model each action as a dated cash event. Enter the monthly saving from the month it starts, severance as a one-time outflow, and bridge proceeds in the month they are expected to fund. Then add the note terms: interest accrual, maturity date, and conversion dilution.
How often should scenarios be refreshed?
Monthly, after the close, with actuals replacing forecast months in all three cases. Refresh off-cycle after a material event, such as a lost top customer, a signed term sheet, or a change in headcount plan.
How does the zero-cash date move under each case?
It moves with the size and timing of each assumption. In the worked example, flat collections pull it from month 19.3 to month 16.0, a $96,000 monthly cut in month 5 pushes it to month 24.2, and a $750,000 bridge in month 9 pushes it to month 30.0.
Sources: Financial Accounting Standards Board, ASU 2014-15 (Subtopic 205-40); 29 U.S.C. §§ 2101–2102; Board of Governors of the Federal Reserve System, H.15 Selected Interest Rates (all accessed November 2026). The company, cash balances, cost cut, trigger, response times, and note terms in the worked example are illustrative.
