You can claim your fiancé as a dependent on your federal income taxes if that person meets certain Internal Revenue Service requirements.
To qualify as a dependent, your fiancé' must have lived with you for the entire calendar year and listed your home as their official residence for the full year.
If your fiancé' has gross income above a certain amount ($5,050 for tax year 2024), you can't claim her as a dependent.
If your fiancé is already being claimed as a dependent by another person, you can't also claim her as a dependent.
You can use this IRS tool, Whom may I claim as a dependent? to determine if your fiancé can be claimed as your dependent.
Click here for "Can I Claim a Boyfriend/Girlfriend as a Dependent on Income Taxes?"