Regarding the calculation of the Parenting Time Offset, the Michigan Child Support Formula (MCSF) Manual states:
Presumably the math of the Parenting Time Offset is designed to reflect this policy decision. How accurate is the MCSF Parenting Time Offset calculation, using only child-specific food expenditures as a benchmark?
Food expenditures rise and fall in a perfectly linear relationship to the number of days. A divorced parent that has the children 30% of the year, for example, needs 30% of the annual food budget. The Michigan Child Support Formula reduces support payments to reflect the direct spending that a non-custodial parent (NCP) accrues during their overnights but it does so by allotting child-rearing budgets on a cubed scale.
The USDA publishes a set of menu costs for food, broken down by age, gender and quality of the diet. There are four levels: Thrifty, Low-Cost, Moderate-Cost and Liberal. According to the USDA in 2010 the estimated cost of food for one child aged 9 to 11, for example, is as follows:
$141.80 per month ($4.66 daily)
$186 per month ($6.12 daily)
$239.90 per month ($7.89 daily)
$280.10 per month ($9.21 daily)
How many overnights must an NCP have with two children before the state credits them with feeding their children?
This graph above shows the total cost in food for each number of days, and the annual MCSF-based NCP PTO credit for a family with $6,000 combined net monthly income. (The chart stops at 128 days—formerly the first point at which NCPs were credited with more than $0 spending.) The assumptions are: two children between the ages of 9 and 11, and the USDA moderate-cost food plan of $7.89 per day per child. Under these circumstances, the state formula does not credit the NCP with a budget large enough to feed the children until 117 days. An NCP with fewer than 117 overnights is credited with negative funds for child-rearing after feeding the children. Conversely, NCP food expenditures equal custodial parent savings on food.
It turns out that the biggest annual budget deficit created just from basic food expenditures occurs at 74 overnights. This is almost exactly equal to the commonly used standard assumption of 75 overnights for half of all weekends, vacations and holidays. At 74 overnights, the USDA moderate-cost menu for two children is $1167, or $849 greater than the NCPs total state-allotted offset of $319 annually. In other words, after simply feeding two children, the NCP is faced with an offset of negative $849 for all considerations toward shelter, transportation, clothes, toys and entertainment 20% of the year. Conversely, at 74 overnights custodial parent savings on food alone is $1167, $849 greater than the $319 support reduction for the NCP.