In Japan since 2003 there have been two ways to calculate child support. The first way is through the use of certain charts created by the “Tokyo and Osaka Child Support Research Group” which determine child support obligations based upon the income levels of the parents and the age(s) of the children. The Charts are published on the website of the Tokyo Family Court. They are simple to apply since all that is required is the income of each parent, whether the income is salary or self-employment and the number of children.
The Charts make it inappropriate to use the "child support calculators" for Japan that are still on several online websites.
The second way to calculate child support in Japan is to apply an extremely complicated system whereby gross income figures are reduced by a range of expenses, including national and state taxes, social insurance contributions, employment-related expenses and so-called “special” expenses, including living expenses, and the resulting figures are then used in specified formulas. The expense figures are usually calculated with reference to standardized tables, which vary according to the locality within Japan. The results of applying the formulas are usually significantly lower than applying the figures that are produced by the Charts.
In practice, Japanese courts rarely issue child support orders resulting from contested situations. Instead, the parties themselves usually negotiate the figures, often with the assistance of court-appointed mediators. The figures in the Charts are merely “maximum” starting points, from which significant reductions are typically made for special circumstances, such as the father's health problems, or his pre-existing obligations to support other family members.
The system to collect child support is extremely weak in Japan. Indeed, surveys show that that only 10% to 20% of fathers pay the correct level of child support. For this reason, child support payments are invariably reduced from the Chart levels in order to secure the active consent of father.