My daughter became non-dependent and moved out in '21. The next question is whether she paid half the cost of the expenses and support - during her time w us or for 2021?

If she was under the age of 19 or a full time student under the age of 24, you cannot claim her as a dependent since she did not live in your home for over 6 months of year per the Qualifying Child rules.

If she was age 19 or older, if you did not provide over one-half of her support for the year you cannot claim her as a dependent under the Qualifying Relative rules.

Use this IRS worksheet to calculate support - https://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf

The minute she said I DO you lost her as a dependent ... she gets to file a joint return with her husband.