Former "Nip/Tuck" star Dylan Walsh is officially divorced from his ex-wife -- but guy shoulda signed a pre-nup ... because the split's gonna cost him half of pretty much everything, including his "Nip/Tuck" money.
The divorce decree was signed by a judge last week -- and according to the divorce docs, Walsh agreed to pay his actress ex-wife Joanna Going half of his royalties from "Nip/Tuck," a couple movies, an "SVU" episode, and more.
Meanwhile, Going agreed to pay him half of her royalties from work she did during their marriage -- including acting work on random shows like "CSI," and "Criminal Minds."
Since Walsh made out with more than Going, Walsh also agreed to ante up an extra $118,376 to even out the spoils.
As for their 9-year-old daughter -- Walsh and Going have agreed to split legal custody.
Walsh -- who makes $93,000 per episode on his new show "Unforgettable" -- has agreed to pay roughly $4,300 from each paycheck in child support. Oh yeah, he also has to pay a boat load of spousal support until 2015.
Walsh filed for divorce in 2010. They got married in 2004.
The lesson -- sign a pre-nup.