The challenges that we are facing is the probability of missing a vital piece to the design or the client needs. There might be something that I need to include or may have overlooked which could cost our company money. In a similar project as the Interior Designer you must budget for all the different phases of the project from the beginning to end. The TBC is what to be done and how much it is to cost.
If the budget is really off such as not including the proper amount of construction cost or remodel the client may not expect to pay for something that they were not aware of. There could also be the cost of if you have agreed to be paid hourly or a set fee, there could be times that unexpected time lines come into play and either could make more money on a project or lose money for mistakes that have occurred.