Calculations are usually done on average income.  When income can come and go, the courts will often take an average for the year to get a better idea of the monthly income.  This keeps the parties from having to file modifications during the seasons when temporary income kicks back in. If you know that the temporary income won't come back, you may just want to see if you and your ex- can agree on child support based on the regular income-- this will be cheaper for both of you so that you don't have to file a modification later when the income has gone away.Either way, you should let the court know what your income is, how you calculated the child support, and the agreements related to that support -- most of the time the court will approve any reasonable agreements-- especially since you are not trying to completely dodge your support obligation.