This is a good example of how divorce lawyers (and family court judges) cause trouble because they're not familiar with the tax laws. It's not clear what being "entitled to" a percentage of her military retirement means. The decree apparently doesn't say anything about how you are going to get the money that you are "entitled to." As VolvoGirl said in the first reply above, it should have been set up as a QDRO. But it wasn't. Your ex is paying you herself and there is no QDRO. So I'm going to change my consultation recommendation again. If you don't want to treat it as alimony I think you need a good tax lawyer to straighten it out, or maybe a tax lawyer and a divorce lawyer working together. I don't know if it's possible to get a QDRO now, or if DFAS would honor it now. You might need to have the divorce decree revised.
If you end up with a QDRO you will get a Form 1099-R each year, and you will just enter the 1099-R in your tax return. If the conclusion is that it's alimony, you will enter it in your tax return as alimony received, which will be taxable income to you. Actually it's not clear to me why you think it's tax-free. Military retirement income is taxable. If you did have a QDRO it would be taxable income.
You said you've been getting these payments from your ex for over 10 years. How has it been shown on your tax return up to now? What form and line number is it on? Or have you just not been reporting it?
By the way, since you also included the child support section, I'll just point out that child support that you receive is not taxable income and you do not enter it anywhere in your tax return. (Another example of poor drafting of the decree, I think, is that it does not specify when the child support payments end. But that's not a tax issue.)
The bottom line is that the simplest solution is to enter the payments from your ex as alimony received, even if you don't think of it as alimony. If you do that, you don't need any lawyers, but you have to pay tax on the income. If you don't want to enter it as alimony, we can't help you here. You will need in-person professional help.
