When a film runs out of money, the cause is usually something the budget assumed without saying so, and it turned out to be false: that the days would be 12 hours, that the pound would stay where it was in March, that the tax credit would land in September. Early passes on any budget are educated guesses from the budgeting team's experience and standard rates. As prep goes on and department heads price their own areas, those guesses get replaced with quotes. The assumptions underneath often don't get revisited at all.
This post is about making those assumptions visible, pricing them, and funding the ones that can hurt you. It pairs with what is a production budget, which covers how the budget itself is built.
The budget is a box
Once a financier approves a budget, that total becomes the greenlight number, and the production has to fit inside it. Every creative and logistical decision after that is a trade inside the box. A second unit day means something else gives. A bigger stunt means fewer background, or one less location.
That's why the production accountant and line producer care so much about what the budget assumed. If the box was drawn around 12-hour days and the show is shooting 14, the box is already too small, even though no single decision looks like an overspend.
The assumptions page
Attach an assumptions page to every version of the budget. It's usually one or two pages and reads like a list of conditions. A realistic one for an independent feature:
| Assumption | What the budget uses | Who confirms |
|---|---|---|
| Shoot days | 22 days, 5-day weeks, 1 company move per week average | 1st AD from the stripboard |
| Hours | 12 hours elapsed from crew call, 1 hour meal | 1st AD, UPM |
| Prep and wrap | 4 weeks prep for keys, 1 week wrap | Line producer |
| Union status | Non-union crew; cast under SAG-AFTRA Low Budget Theatrical Agreement | Producer, SAG-AFTRA signatory application |
| Locations | 14 practical locations in one metro area, no stage | Location manager |
| Cast deals | Two leads at agreed fees; supporting cast as placeholders | Producer, casting |
| Night work | 4 nights, all exteriors | 1st AD |
| Post | 16 weeks to picture lock, 6 weeks finishing, 40 VFX shots | Post supervisor |
| Currency | All spend in USD | Accountant |
| Incentive | State credit on qualified spend, net of sale discount, received 9 months after wrap | Accountant, incentive counsel |
| Financing | Equity closed before prep; incentive loan closed before first shoot day | Producer, lender |
Every row is a place the budget can break. The second column also tells a financier or bond company exactly what they're approving, which saves arguments later.
Stress-testing the expensive ones
Not every assumption deserves the same attention. Price what happens if each one breaks by a plausible amount, then sort by dollars. Three examples show how quickly the numbers get large.
Hours per day
Take a crew of 30 paid on overtime rules like those in the IATSE Low Budget Theatrical Agreement, which pays time and a half after 8 hours worked up to 13 hours elapsed from call, and double time after 13 hours elapsed (per IATSE Local 44's 2024 terms sheet for that agreement). Assume an average straight rate of $35 an hour and a 1-hour meal.
The budget assumes 12 hours elapsed, so 11 worked: 8 hours straight and 3 at time and a half.
- Per person: (8 x $35) + (3 x $52.50) = $280 + $157.50 = $437.50
The show averages 13.5 hours elapsed, so 12.5 worked: 8 straight, 4 at time and a half (to 13 elapsed), and 0.5 at double time.
- Per person: $280 + (4 x $52.50) + (0.5 x $70) = $280 + $210 + $35 = $525.00
The difference is $87.50 per person per day. Across 30 people and 22 days: $87.50 x 30 x 22 = $57,750, before fringes and before meal penalties from the late lunches that usually come with long days. That's one assumption, and it's rarely the only one that slips.
Exchange rate
The example above spends only dollars. A US-financed film shooting in the UK doesn't. Say it budgets £4,000,000 of UK spend at an assumed rate of $1.30 to the pound, which is $5,200,000. If the pound strengthens to $1.38 by the time most of the money is spent, the same spend costs $5,520,000. That's $320,000 the budget didn't have, and nobody on the production made a bad decision.
The incentive moves too. If £3,200,000 of that spend qualifies for the UK's Audio-Visual Expenditure Credit, the 34% credit is taxable at the 25% main rate of Corporation Tax, which leaves a net benefit of 25.5%: £3,200,000 x 0.255 = £816,000. At $1.30 that's $1,060,800; at $1.38 it's $1,126,080. The stronger pound helps the credit, but only by $65,280, against $320,000 of extra cost. Financiers who worry about this buy forward currency or hedge, and the budget should say which rate the hedge locked.
Incentive timing
The budget shows a $600,000 net state credit as a source of funds. If the cash arrives nine months after wrap as assumed, and the production borrowed against it, the lender's interest and fees for that period should already be a line in the budget. If the audit slips and the cash arrives fifteen months after wrap, the loan runs six months longer. At an illustrative 10% annual interest on $540,000 borrowed, six extra months cost $540,000 x 0.10 x 0.5 = $27,000. Real terms vary by lender, so replace the rate with your term sheet. Film rebates vs tax credits covers how the incentive type affects timing.
Turning the test into contingency
Once you've priced the plausible breaks, compare them with contingency. A simple version, with illustrative costs for a $2,000,000 feature:
| Break | Plausible cost |
|---|---|
| Average day 1.5 hours longer than assumed | $57,750 plus fringes |
| Two lost exterior days to weather, rescheduled | $70,000 |
| Supporting cast placeholders come in over | $35,000 |
| Incentive cash 6 months late | $27,000 |
| Total if all four happen | about $190,000 plus fringes |
If the budget is $2,000,000 with 10% contingency ($200,000 on a $2,000,000 base, before any bond fee), you're covered for that scenario with very little left for anything else. That might push the producer to buy weather insurance, trim the exterior schedule, or close cast deals before locking. A lower-risk shoot on stages in one city might run the same test and find 10% generous. Film budget contingency goes deeper on sizing.
Assumptions that come from the script
Some of the costliest assumptions hide in scene descriptions. Before locking, read the breakdown for these:
- Weather and time of day. "EXT. BEACH - SUNSET" on three different pages is three evenings of magic hour, not one.
- Crowds. "The stadium erupts" is a background count, a VFX tile plan, or both.
- Vehicles. A car scene can be a process trailer, a stationary car with lighting effects, or a real drive with a camera car and police escort. Each is a different number.
- Minors. Child actors bring studio teacher time and shorter working hours, which change the day count.
- Animals, water, heights, fire. Each adds specialists, safety, and time.
Each of these should become a named row on the assumptions page, with the approach the budget chose.
Collaborating with department heads
A line producer often asks department heads to do rough budgets for their own areas once they're hired. The construction coordinator prices builds, the costume designer prices the number of changes and multiples, and the transportation coordinator prices vehicles and drivers. Their numbers keep the budget tied to the creative decisions actually being made.
Give them the assumptions page first. A costume designer who doesn't know the film shoots 4 nights in the rain won't price doubles for the lead's coat. A transportation coordinator who assumes one company move a week when the board has three will under-price drivers and fuel.
The production accountant's role
On a film, the production accountant runs the show's books day to day. They set up the chart of accounts, manage payroll and payables with their assistants and clerks, reconcile petty cash, and produce the weekly cost report that compares actual and committed costs with the budget. They're the ones who see an assumption breaking first, in the numbers.
A good accountant ties the weekly report back to the assumptions page. If the show averaged 13.2 hours in week one, the cost report projects that forward, not the 12 hours in the budget. The production accountant role page covers the job in detail, and how to read a film cost report explains the columns.
Cash flow is an assumption too
A budget total can be right and the production can still run out of cash, because money arrives later than it goes out. The cash flow schedule lays out, week by week, when each source of funds lands and when each account spends. Deposits on stages and gear, first-week payroll, and location fees all hit before a single frame is shot. If equity funds in tranches or the incentive loan closes late, the gap has to be covered.
If you use Storiara, its Budget module calculates a first-pass budget from the breakdown, schedule, and cast and crew data, including a contingency percentage you set, and exports to Excel. Assumption tracking, cash flow, and cost reports still happen in your own spreadsheets or accounting software.