My ex lost their job and wants support lowered. What happens?
An order stays in force until a court changes it, and a change usually cannot reach back before the date it was asked for. A job loss does not lower support by itself, and an informal agreement between the two of you generally does not either.
That single rule about backdating drives almost everything else here, in both directions.
If you are the one who owes
File immediately. Not when you have found new work, not when the arrears become frightening. The day you know your income has changed. No state will modify child support for a period before the change was requested. Federal law requires that, so there is nowhere that waiting is free. And in some states the clock starts when the other parent is served, not when you file, so do both immediately. Every week of delay is a week you still owe at the old rate, and that debt does not go away.
Keep paying what you can meanwhile. Partial payment demonstrates good faith and reduces what accumulates. Stopping entirely, even with a genuine reason, invites the full enforcement toolkit, and for child support every state is federally required to have it: wage garnishment, state and federal tax refund interception, suspension of driver's, professional and recreational licenses, and liens. Two more are worth knowing before they arrive. Once a state certifies that you owe more than $2,500, the State Department must refuse to issue you a passport and can pull one you already hold, which people usually discover days before a trip. And arrears are reported to the credit bureaus, so they sit on the file that decides your next mortgage or lease. Support arrears also cannot be discharged in bankruptcy at all, not in Chapter 7, not in Chapter 13.
If you are considering a change rather than reacting to one, do that reading first.
Expect the reason to be examined. Courts distinguish between losing a job and choosing to lose one. Where a reduction looks voluntary, or where someone appears to be underemployed on purpose, many states will calculate support on what that person is capable of earning rather than what they are currently earning. Keep evidence of the layoff and of your job search.
If you are the one receiving
Do not agree informally. A private arrangement to accept less usually does not change the order. That sounds like it protects you, and it creates a genuine mess: arrears accrue on paper while you have agreed not to collect them, and untangling that later is its own dispute.
If you agree to a reduction, put it through the court so the order matches reality.
Look at whether the loss is real. A sudden income drop timed neatly to a support review is something courts see often. Payslips, tax filings, and the pattern of spending tell the story, and there are legitimate ways to find out what is actually there.
Do not withhold the children in response. Support and parenting time are separate obligations, and retaliating converts their problem into yours.
What a court generally looks for
A substantial change in circumstances since the last order, one that was not anticipated when the order was made, and one that is ongoing rather than a brief interruption. The exact threshold varies, and some states use a percentage difference as a rough gate.
A short gap between jobs often does not clear that bar. A long-term change in earning capacity usually does.
There is a second route, and almost nobody is told about it. If your case runs through the state child support agency, either parent can ask for a review every three years, and the order gets recalculated against the state's guidelines with no need to prove anything changed at all. It costs nothing to ask. Many states then apply a minimum difference before they will actually adjust the order, so it does not always move the number, but it is free and it does not depend on your reason being good enough.
The practical version
For the payer: file the day it happens, keep paying something, and document the search.
For the recipient: insist any change goes through the court, and build your own projection on the possibility that less arrives for a while. The money side of divorce covers doing that arithmetic before you need it.
What counts as a substantial change, whether income can be imputed, and how far back a modification can reach all vary by state, and the backdating rule in particular is the one worth confirming immediately. If your income has changed, talk to a licensed family-law attorney this week rather than next month.