Okay, is there an actual order in place that establishes the custody arrangement? Or, is the order just for child support? In other words, when you say that the mother has denied visitation, did a court agree with her and say that your son could not have visitation, and is this reflected in a court order? Or, has visitation never been established, and the mother just says it's not going to happen? If no custody order has been established, your son has the right to seek visitation. Parents are generally not denied visitation rights unless they have abused the child or are in some way a danger to the child. However, since it has been ten years without visitation, if your son would like to file a petition to establish child visitation, he will probably have to explain to the court why he waited so long to do so, and he should propose a visitation schedule which takes into account the fact that the child has had little to no contact with him during the child's life. This will be the hardest factor in establishing visitation at this point, should your son wish to do so.
Your son may want to file for a modification of child support. That way, he will be able to offer evidence of what he actually earns as opposed to the state's assumption. The court will also ask the mother for records showing what she earns. $500 a month seems a little high for one child. I have looked at the Iowa Child Support Guidelines, and even assuming a full-time income at $10.00 an hour, with the mother earning nothing (which seems to not be the case here), the payment amount should be around $400 a month.
If your son does not have money for an attorney and would like to hire an attorney, he could see if he qualifies for free or low-cost legal aid. Here is a link to some organizations which provide free or low-cost legal service to those in need: http://ptla.org/ptlasite/links/services.htm.
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