Defensible assumptions

Common expense assumptions by family size.

Use ranges when the case omits expenses. Label them as assumptions and keep them conservative.

75-minute solverSlide orderPriority rankingExpense assumptionsSpecific case tipsMust-haves
Monthly expenseSingleCoupleFamily of 4Notes
Groceries/household basics$300–$500$550–$850$850–$1,300Use higher end for metro areas or teenagers.
Utilities not listed$150–$250$200–$350$250–$450Separate from rent/mortgage if not included.
Transportation fuel/maintenance$150–$350$300–$650$450–$900Older cars need a repair sinking fund.
Phone/internet$80–$160$140–$260$200–$350Flag cheaper plans as a savings lever.
Child costs$200–$1,200+Varies widely: childcare, activities, school supplies.
Medical out-of-pocket$50–$200$100–$350$200–$600Higher for HDHP, prescriptions, or chronic issues.
Giving/family support0–10% income0–10% income0–10% incomeRespect values, but set a monthly cap when debt is high.
Emergency fund target3–6 months essentials3–6 months essentials3–6 months essentialsUse 6 months for single income, unstable work, health concerns.

Presentation tip: put assumptions in a small box on the cash-flow slide so judges know you did not invent facts silently.