as far as i've been told, researched, lookedup.... texas is pretty cut and dry. NCP pays % of income, doesn't matter who makes more or whatever else.
I could make 300K and my ex could make min wage. he'd still have to pay 25%. if given 50/50, nobody pays.
far as i've found, the PCP's income has no bearing whatsoever on CS. not in texas anyway.
Texas loves expanded visitation, which gives like a 60/40 split or there abouts. unless the NCP doesn't wish to exercise of course.
I was also advised that standard in this area anyway, if there is 1 child the deduction goes to PCP, two and the deductions are split (mine are, I had to agree)
so it would depend on # of kids.....unless a parent gave up the option. but the #1 mediator in DFW told me that standard practice in the courts here is 1 to PCP, 2 split....3 two to PCP, etc.
Your interpretation of child support seems about right, on the surface:
Texas Child Support Calculator - AllLaw.com
However, note that the calculator says (near the top) that it is not meant to be used for shared custody situations. I think you need to search harder (or ask an attorney) what would be typical in a shared custody situation. I suspect that if his income is 10 times yours, he's going to be paying child support, even in a shared custody situation.
I don't know what the standard is for deductions in TX so you may be right. HOWEVER, keep in mind that IRS rules MUST be followed. The parent where the children spend the most nights automatically gets all the deductions unless the appropriate form is signed by the custodial parent. So if you are the custodial parent and the court orders that you give one or more deductions to the other parent, you will need to sign the form (I can't remember the number, but it might be 8443) EVERY YEAR.
Now that you've clarified the situation, let's go back to basics. As I understand it, you're still trying to reach an agreement on child support, custody, etc and hope to reach an amicable agreement without spending excess money on lawyers (keep in mind, however, that it's only amicable as long as BOTH of you agree). I would suggest:
1. Even though you're trying to avoid expenses, I would have an attorney review whatever you agree to before submitting it to the court.
2. Before doing anything, I would consult with an attorney. Many attorneys will give you an initial consultation for free (so you can ask questions like the shared custody / support question above), but even if you have to pay a couple hundred dollars, it will probably be helpful for you to go into the negotiations with an idea of what to expect.
3. I would first settle the child custody decision on the basis of what's best for the kids. If the two of you live far apart, there's no way that a 50:50 arrangement will work. If you're unable to agree on things like school, etc, it won't work. If, OTOH, you're close together, have flexible schedules, and are willing to work to make shared custody work, it may well be what's best for the kids. But this decision should be made on the basis of the kids' needs, not your or your husband's financial needs. After all, if you can't agree, the court will make the decision on the basis of the kids' needs.
4. Once the custody decision is made, then look at child support. While I think TX is too extreme (fixed percentage of income doesn't take into account any special circumstances. For example, if you were independently wealthy and your stbx were barely getting by, it's not particularly fair), that is what the court will use if the two of you can't agree. Assuming that you will have primary custody, start with the TX calculation (remember, they use a max of $6 K per month in the calculation) to get an idea of what the court would order. That may change if you have shared custody (but rely on whatever the lawyer tells you in step 2 or any research you can find on shared custody).
However, since you're presumably trying to negotiate what's fair rather than simply throwing it to the court to decide, I would look at what it would be in surrounding states. In OK, for example, the max figure used in the calculations is about $150 K per year, although support can be increased if income is higher. At the same time, both parent's income is considered, as is the number of nights the children spend in each home. REMEMBER, this has no legal validity in TX and would mean absolutely nothing to the judge. It might, however, give you an idea of what different people would consider to be fair. If the two of you aren't interested in considering other options, then just throw it back on the courts and accept the state guidelines.
Finally, since you state that it's an amicable divorce, you may end up having to rely on stbx's sense of fairness. I agreed to considerably higher child support and alimony payments than my state guidelines because my money will eventually go to my daughter, anyway, and I'd rather have her be comfortable at both homes. Your ex may feel the same way.
It may be helpful to have mediation to settle the issues if you can't agree. It will be cheaper than a legal battle and probably more satisfactory. Given your circumstances, it is likely that your ex would be expected to pay for it.
Bottom line, though, is that if your ex wants to play hardball, you could end up with a custody battle - which doesn't help anyone. You really need to get that initial consultation with an attorney. If possible, you may want to contact legal aid.