no you can not file a joint return with your ex. to file a joint return you must be legally married at 11:59:59pm on 12/31/2021
the tax laws may not follow the divorce decree as to claiming the children as dependents. it's the tax laws that control.
to qualify as head of household a taxpayer must meet all of these tests. IRC Sec 2(b)
1) the taxpayer is not married at the end of the year
2) the taxpayer paid more than 1/2 the cost of keeping up his/her home
3) the home was the principal residence for more than 1/2 the year of either of the following:
= the taxpayer's qualifying child
= the taxpayer's qualifying relative who is the taxpayer's dependent with certain exceptions
4) the taxpayer is a US citizen or resident during the year.
not meeting all these tests means that an unmarried taxpayer can only use the single filing status
the custodial parent is the one that can claim the qualifying children as dependents unless that parent furnishes the non-custodial parent with form 8332.
if the divorce decree grants the non-custodial parent the right to claim the qualifying children as dependents, failure by the custodial parent to comply could result in that parent being held in contempt of court.
