found this on CS modification in New York:
When can child support orders be changed?Child support orders cannot be changed on a whim or because a court thinks that "it is time." It must be based on evidence proving that there is good reason to make the change. This usually requires that a person who wants to make the change show a changed circumstance. You must show that the facts that existed when the last order was entered have changed. (In the many years a child support order is in place, the parent's circumstances may change many times.) For example, in New York, if one parent's income has changed (either gone up or down) by at least 25%, this is considered a big enough change to require a change in the support order. You can request a modification for a lesser change in income, but will not necessarily be guaranteed a change in the support order.
What circumstances might require a change in support?
Many different scenarios can create changed circumstances. For example, if the paying parent has had a large increase in income, the court can order the child support increased. Or, if the child's needs grow, such as if the child becomes ill or disabled, the amount of support can be ordered raised. Sometimes the mere passage of time creates the changed circumstances. For example, as a child grows older, it becomes more expensive to buy clothes, food and other necessities. These increased expenses can be enough to justify a raise in the support order.
Support can also be reduced if you can show why this would be fair. For example, support payments may be reduced if the custodial parent inherits money, gets a large raise or otherwise has an increased ability to support the children. Or, if the paying parent loses his or her job, the court can be asked to reduce support during the period of unemployment.
I wonder if my job (which by no means pays really well - look at my sig., I'm a librarian) constitutes "an increased ability to support the children"