What documents qualify to prove seperate maintenance was paid? My ex and I separated in Sept '18 and we didn't put anything in formal writing. Would I still be able to claim it if I provided a letter

[zachlogston]

From my chain of command stating the Marine Corps Order that required me to pay it, when I started paying it, and how much along with my bank statements that show I paid?

[ReginaM]

Yes, if you have a letter from the Marine Corp ordering you to pay separate maintenance for your former spouse, you may claim this as alimony payments, provided that the following rules are met:

• You and your spouse or former spouse do not file a joint return with each other,
• You pay in cash (including checks or money orders),
• The payment is received by (or on behalf of) your spouse or former spouse,
• The divorce or separate maintenance decree or written separation agreement does not say the payment is not alimony,
• If legally separated under a decree of divorce or separate maintenance, you and your former spouse are not members of the same household when you make the payment,
• You have no liability to make the payment (in cash or property) after the death of your spouse or former spouse, and
• Your payment is not treated as child support or a property settlement.

For more information see Publication 504.

[Carl]

What documents qualify to prove seperate maintenance was paid?

This is a legal question, not a tax question. Even the response from a "tax expert" should be taken as "advice" at best, and nothing else. I would highly suggest you contact your base legal office or the legal authority dealing with your situation for a definitive answer to your question.