Is there any type of law in Iowa that states how much you can charge for a late fee? I went to register my kids for soccer (it is $60 to enter) but the entry was due Jan. 30. I wasn't aware of this date as I did not receive the mailing since I wasn't on their mailing list. Apparently they have a $50 late entry fee, so now it costs $110 to enter, is this even legal?

A private entity can charge whatever it wants. You are not compelled to join.