You must file your own returns since you are not legally married. And you cannot both claim the full amount of property tax paid since that would be double dipping. Enter the amount that each of you paid.
It might not even make any difference. Did you purchase the home in 2021?
HOMEOWNERSHIP DEDUCTIONS
It is very hard for a lot of people to use itemized deductions now that the standard deduction is so much higher. Your home ownership may not have any effect on your tax due or refund, especially if you purchased the house late in the year.
Standard Deduction
Your itemized deductions have to be more than your standard deduction before you will see a change in your tax owed or tax refund. The deductions you enter do not necessarily count “dollar for dollar;” many of them are subject to meeting tough thresholds—medical expenses, for example, must meet a threshold that is pretty hard to reach. The software program uses all the IRS rules that apply to the expenses you enter, and it tells you if you have enough to use your itemized deductions or if using the standard deduction is more advantageous for you. Under the new tax laws, some deductions have been capped—there is a $10,000 limit to the itemized deductions for state, local, property and sales taxes.
2021 STANDARD DEDUCTION AMOUNTS
SINGLE $12,550 (65 or older + $1700)
MARRIED FILING SEPARATELY $12,550 (65 or older + $1350)
MARRIED FILING JOINTLY $25,100 (65 or older + $1350 per spouse)
HEAD OF HOUSEHOLD $18,800 (65 or older +$1700)
Legally Blind + $1350
Thank you! We purchased the home the last week of December in 2020 so we haven't had to claim any property taxes till now. Can I just use the "taxes paid from escrow" cell in the 1098 form or should I be waiting for a different form?
Yes, you can use the property tax number shown on the 1098 from your mortgage company reporting taxes paid from escrow.
Be sure that you each enter half of the amount in your separate returns. The same holds true for the mortgage interest and any private mortgage insurance amounts shown on the 1098.