One excuse that people sometimes give for failing to pay child support is that they simply can't afford it. Life is expensive. They have to pay rent and utilities. They have to buy food. They just don't earn enough to make ends meet and still send that child support check off to an ex every month.
Certainly, tough economic situations do play a role in this process in some cases. For instance, someone may lose his or her job and not realize that it's possible to get a court-ordered modification to the original child support order. Those original payments appear impossible.
However, one study showed that the issue may not be as ubiquitous as some assume. For instance, it found that 2.5 million fathers who did not live with their children and neglected to pay any support were also in poverty on their own. By comparison, 4.5 million fathers who failed to pay were not poor and had "no apparent financial reason to avoid this responsibility."
Even when fathers claim to be too poor to pay, it is worth noting that child support calculations take earnings into account. You're not going to be ordered to pay $2,000 per month if you earn $2,500 per month. Plus, as noted above, modifications are possible when there is a significant change in employment.
As such, it's important for people on both sides of this equation to know all of the legal rights that they have. Those who are owed need to know how to obtain payments, while those who honestly can't pay need to know about modifications to make payments affordable again.
Source: Urban, "Poor Dads Who Don’t Pay Child Support: Deadbeats or Disadvantaged?," Elaine Sorensen and Chava Zibman, accessed Feb. 23, 2018