IRS publication 504 explains the rules for alimony including payments for shared assets. This gets complicated, and you may want to have your situation reviewed by a professional. If you report alimony payments and your spouse does not agree with the amount and report a matching amount of income, you both may get audited. So you want to be on the same page, ideally.
Division of marital assets or property is not alimony and is not taxable or deductible.
https://www.irs.gov/forms-pubs/about-publication-504
The one situation directly addressed in publication 504 is the home. If you and your spouse co-own the home, and you don't live there, and you are ordered to pay half the mortgage, then that is just you paying for your own asset, it is not alimony. But, you can then deduct half the interest and half the property taxes on your schedule A. If you are ordered to pay the entire mortgage, and you don't live there, then half the payment is alimony, and half is you paying for your own asset. Your ex gets to deduct half the mortgage interest and property taxes (because it is considered "paid" from the half of the payment that is alimony that is taxable to her) and you deduct half the interest and taxes.
If you are ordered to pay car payments for a car that your ex owns, that is probably alimony. If you are ordered to pay off a car you own so it can be transferred to your ex as part of a division of property, that is probably not alimony. Money you are ordered to pay her that she uses for bills is possibly alimony.
When the order is not clear about what is division of property and what is spousal maintenance, you probably should get it reviewed by a tax professional in your area.
