Thanks for the added info.
If the amount of commissions was to be a 50/50 split after tax, then the question is: what is the definition of after tax for the purposes of the agreement.
After tax, can be the amount of commissions paid after withholding based upon the ex-husband's W-4
, or it can be the amount of net income after the ex-husband has filed a final Form 1040
return with the IRS.
If the agreement is silent on how "after tax" is calculated, then the parties have a dispute that may require an arbitrator or judge to resolve.
As for the ex-wife's tax obligation, under federal tax law, a transfer of marital property
incident to a divorce made within 12 months is generally not subject to income tax. But, what you describe here is not marital property -- it's future earnings, which is generally considered spousal support, when there is an agreement for such support.
Since you state that there is a separate agreement for spousal support, these payments would be either: (1) a "gift" from ex-husband to ex-wife, and thus not taxable (though reportable) to ex-husband, unless the aggregate amount of payments exceeds $5,250,000 during the ex-husband's lifetime; or (2) taxable income to ex-wife, but not deductible to ex-husband (a really, really bad deal for him, because this all should have been dealt with as additional spousal support).
In sum, this agreement is quite a hornet's nest. I'd love to provide a perfect solution here, but the reality is that there are probably a half dozen different ways to skin this cat. If it were me, I would try to revise the spousal support agreement to include these payments, because that would make the payments tax deductible to ex-husband.
Please let me know if my answer is helpful. And, thanks for using justanswer.com!