can alimony exist prior to divorce for the purpose of US tax filing?

Question

A married couple separated in the first half of 2014 and together signed an uncontested divorce decree which specified alimony payments. The divorce case has been filed with the court but not finalized, so the parties were married at the end of 2014 and are still married at the time of filing taxes. For the purpose of IRS rules, I believe this to qualify as a separation agreement, or possibly a written instrument incident to a divorce decree.

Can anyone comment on whether this is a reasonable interpretation of the meaning of "alimony," and/or explain how the IRS might view it if the alimony-paying spouse submitted a tax return as "Married Filing Singly" reporting the alimony paid as a deduction from taxable income?

From IRS Publication 504:

Divorce or separation instrument. The term “divorce or separation instrument” means:

• A decree of divorce or separate maintenance or a written instrument incident to that decree,
• A written separation agreement, or
• A decree or any type of court order requiring a spouse to make payments for the support or maintenance of the other spouse. This includes a temporary decree, an interlocutory (not final) decree, and a decree of alimony pendente lite (while awaiting action on the final decree or agreement).

Answer 1

You've already seen the answer from your link.

"This includes a temporary decree, an interlocutory (not final) decree, and a decree of alimony pendente lite (while awaiting action on the final decree or agreement)."

Do you have either of those?

As far as being married, I believe the rules that if you are married on 12/31, the you are considered married for that year. Still being married at filing is meaningless for the previous tax year.