We do not have a custody/consent order in place, nor have I filed anything with CSE. If I were to try to get back child support for the past 3 years, would I use the child support calculator to determine the amount owed? Or would I add up actual expenses over this period of time? I had heard somewhere that back child support only comes into play when you’ve filed a claim and they’ve not paid it.
Yes, you will have to file a suit and ask for retroactive support to get the relief sought. The Child Support Guidelines were revised to say that retroactive support can be calculated using the guidelines, but there are some contentions between whether this is consistent with case law. I would be prepared to argue both the guidelines and actual expenses in the event the judge you are in front of has a preference.