I am going through a divorce and my stbx is asking for us to file our taxes now for next year, 2026. We have some capital gain taxes too. Is this possible?

[VolvoGirl]

File what now?  A tax return for 2025?   No you can’t file a 2025 return until next January 2026.   And your filing status is determined on Dec 31. If you are divorced by 12/31 you file as Single or Head of Household if you have a qualifying dependent.   So if you get divorced in 2025 you can’t file 2025 as married Joint and or Married filing Separate.   

[Mike9241]

as a stbx  it's likely you won't be married to that person on 12/31/2025 preventing filing a joint return with that person.however if you remarry on or before 12/31/2025 you can file a joint return with your ns (new spouse) 

[rjs]

Talk to your divorce lawyer about the income tax issues. Make sure that any tax considerations are clearly spelled out in the divorce decree, and that the decree is in keeping with the tax laws. Make sure it's clear who the capital gains belong to.

If your divorce is not final by the end of 2025, you need to come to an agreement about whether you will file jointly or separately for 2025. Either way you need to cooperate with each other for tax filing.

It would be a good idea to get a tax professional to work with your lawyer, and to review the divorce decree before it's finalized. We often see questions from divorced people who have tax problems because their divorce decree has a provision that's not permitted under the tax laws, or because a tax issue was not addressed in the decree. Many divorce lawyers, and family court judges, know a lot less about tax law than they think they do.

[Opus 17]

You file one tax return for the entire year.  Most people are on a calendar year (Jan 1 through Dec 31).  Changing to a different year is difficult and probably requires an accountant to help, and is not recommended for individuals (sometimes companies do this). 

You can't file a return for half the year before the divorce and half the year after the divorce.  One return for the whole year, containing all the income, deductions and credits for that year.  

If you are single on December 31, you file as single (or maybe as head of household) even if you were married for part of the year.  If you remarry to spouse #2 on or before December 31, then you file as though you were married to spouse #2 for the entire year, even though you were married to spouse #1 for part of the year and single for part of the year. 

[Opus 17]

If your goal is to figure out how to minimize your taxes, or figure out what is the fair way to divide any tax responsibilities, you should talk to an accountant who can review all your facts and personally advise you.