Certain conditions have to be met for you to claim her.
- Your daughter and her husband must both agree to file their tax returns with a filing status of Married Filing Separate
- Your daughter must agree to not take her self exemption, and her husband must agree to also not take her exemption on his Married Filing Separate tax return.
- Your daughter must agree to not claim any dependents on her MFS tax return (if there are any dependents she would be qualified to claim otherwise.)
If they both agree to the above terms and file as indicated, then you can claim your daughter as a dependent on your tax return for the 2017 tax year.