A film budget is organised into two halves that behave completely differently. The distinction is old accounting terminology, and it explains where money is committed and where it escapes.
The line separates people from process
Above-the-line covers the principal creative participants, typically the writer, director, producers and lead cast, along with the underlying rights to the material.
Below-the-line covers everything required to physically make the film, including crew, equipment, locations, construction, transport and post-production.
The terminology comes from budget forms on which a literal line divided the two sections, and it survives because the two categories are negotiated at different times by different people.
Above-the-line costs are largely fixed in advance
These are agreed during development, often long before a shooting schedule exists, and they do not change if the shoot runs longer than planned.
They are also the least flexible part of the budget, since the participants attached to a film are frequently the reason it was financed at all.
Deferred fees and back-end participation are used to reduce the cash cost here, moving compensation from the production budget into a share of later revenue.
Below-the-line costs scale with time
Crew are paid by the week, equipment is hired by the day, and locations are charged for the period they are occupied.
An extra shooting day therefore costs a predictable amount across dozens of lines at once, which is why schedule protection dominates production planning.
Weather, illness and technical failure all translate into schedule, which is the mechanism by which most overruns actually occur.
Contingency and completion cover the gap
Budgets include a contingency allowance, typically a percentage of the below-the-line total, because some overrun is expected rather than exceptional.
Financiers frequently require a completion guarantee, under which a third party takes responsibility for delivering the film if costs exceed the budget.
The guarantor's ability to take control of a production is what makes the guarantee meaningful, and its presence changes how a production is supervised.
Marketing sits outside the production budget entirely
Prints and advertising costs are accounted for separately and are frequently comparable in scale to the cost of making the film.
Because they are decided after a film is finished, they reflect the distributor's confidence rather than the original plan.
Reported production budgets therefore understate what a film must earn, which is why headline figures and break-even estimates rarely match.