I hope this gets to you in time (although it probably hasn't...sorry, just joined today), but before you write that first word, find out what the laws are in your state re: child support. This isn't to say that you will have to USE these laws against him (he just may be a flaky guy, and simply needs a reminder...best case scenario), but, your state may have weird laws against this kind of contact depending on your divorce agreement.
However, there are a few general rules to keep in mind if you do decide to make this contact:
1)Remember what "Mom" always said, "You can catch more flies with honey then you can with vinegar." Guys are like this too. A gentle reminder of how he cares for his daughter along with a simple list of needs (ie: uniforms for school, scouts, food, etc.) that you are having difficulty meeting due to lack of funds will go a lot further then "Hey jerk, pay us the money or I will SUE!"
2) Remember, this is not about you NOR your ex-husband, it is about getting what your daughter needs. Keep the emphasis on that instead of any past grudges you may bear.
3) If, and ONLY if you are truly desperate for the funds would I bring up potential consequences at the END of the letter (not the beginning, soften him up first) by saying something like: "I'm sure this has slipped your mind, but I'd rather keep this civil then to see you get your wages garnished."
IF this letter doesn't bring any response, I would then go to a lawyer or social worker (depending on where you live) and then let them deal with it. Sometimes you just have to let the professionals take over.
Reply from Brigitta McGregor (La Place - U.S.A.)