It is very important as you are creating feature films to understand what your enemies are. Aside from the obvious things like technical difficulties, you need to be aware that there are other problems that you can encounter which will adversely affect your budget, and possibly hurt your film as well. Knowing in advance what these problems are is critical to making sure that you are successful even if the problems appear. Your budget will always be prone to problems, but your worst enemy is likely right in front of you and you are just overlooking it.
If you stop and think about the various aspects of your budget, you are probably thinking about salaries, and equipment plus perhaps even location fees and permits. These are all aspects that can eat at your budget, but because they are accounted for, they generally do not hurt you too badly. The biggest threat to the budget will be those expenses that are not accounted for. This can include anything that you forget to include, which will undoubtedly be extremely expensive, no matter how minor it might seem.
One such example of an unexpected expense could be a damage charge. If you have rented equipment that has managed to be damaged somehow in the shoot, you can look forward to a charge for the damage. Additionally, if you are late returning the equipment you can look forward to a late charge being added onto the rental. This can often be as much as 100% of the rental costs, which will really impact your budget. Looking to curb these expenses obviously means you need to stay on time for your schedule, but it also means taking very good care of the equipment that you have rented.
Many filmmakers are unaware of the need to rent a location until they have been hit with a fine. These expenses have to be taken into account as well and will often throw your budget completely off track. Typically speaking it is best to save at least 10% of your budget for these unexpected expenses so after you are all done, you will still have some money left over. Many budgets need more than just 10% to handle these unexpected expenses, and other budgets do not even use the whole 10%.
Determining exactly how much you will need is often flexible. Typically speaking the larger your budget, and the more equipment you need to rent, the larger the amount that needs to be set aside for the unexpected expenses. If you are able to avoid all of your budget overages, you will be able to save a ton of money that would otherwise be blown.
Filmmakers who are working with a zero budget typically are much more careful about unexpected expenses. This is the type of dedication that you need to take into account anytime you are working on a film so that you can reduce costs. One way to really help keep tabs of the budget is to continuously keep a running tab of expenses. This will be helpful if you are starting to feel like you are getting close to your limit. Knowing when to start getting really tight with the budget is important. You should always avoid spending the unexpected budget on anything that is not considered an unexpected expense since the money will most likely be needed at some point.