Highly recommend you plan to support at current levels regardless of your future income/or lack thereof. Don't know your state, but imputed income is likely to be called into play if you make a choice to stop working and then ask for a reduction.
We are planning on just this thing as we are FIREing in May, but his Child support obligation will continue through the following summer. We wouldn't dream of asking the court to reduce our obligation because we decided not to work.
There is something seriously wrong with that reasoning, and imputing income in a FIRE scenario.
I currently make around $400k/year. For 2 children in most states I'm looking at $60-90k/year child support payment. See the problem?
The problem is the law mistakenly assumes I spend most my net income, which is absurd. I plan to spend ~$40k with partner and 2 kids. I don't want to raise spoiled brats who would "need" $60-90k/year in luxury. If the support payments were ~$20k, that would be reasonable.
The second bigger problem is that $400k/year is soul sucking, and I'm implicitly making more effort now so that I can relax later (FIRE). Think about a lucrative $150k/year gig in remote coal mines @ 16 hours/day. Many people would sacrifice their time now and make bank for a few years, but it doesn't mean they want to make it a permanent lifestyle or that they'd be a deadbeat if they took time off later on, or that they want to spend $60k/year on their kids.
Why would we favor the guy who's been cruising at $30k/year all his life in relative ease, no schooling, no PhD, no big sacrifices, with lower support payments, when the $150k or $400k guys are actually aiming for the same lifestyle but choose to front load their earnings and amortize their expenses over a few years? Maybe the $30k/year guy would be
able to earn $150k if he worked 16 hour days if he bothered trying and sacrificed most of his personal life, but he doesn't want to. Shouldn't we impute a $150k income to him too?
This imputed income rule is wrong and needs to be rethought. Earning $400k/year doesn't mean it's sustainable for you or that it's your life plan to supply this water hose of money to your spoiled wife and kids.
Note that I'd be in favor of imputing income up to the median income level, i.e. ~$50k, but not more. I'm not sure what courts do in practice, but in any case this should be spelled out in law.