Yes, if they lived with you more than half the year (183 nights). 6 months is half the year and 7 months is more than half the year. Selecting the whole year is exactally the same as 7 months.
If you are asked how many months they lived with you answer truthfully, about 9 months. As long as they lived with you more than half of the year, you are the custodial parent which is the important determination for tax purposes.
based on what you said, it appears the father had custody for more time than you did, namely more than half the year.
You can't claim them.
How do you figure that? Even if you consider a "week end" to be 3 days then that is still only about 108 days. ((3 X 52) / 2) + 30 = 108. If the weekend is 2 days then ((2 X 52) /2 + 30) = 82. (assuming 4 weeks is an average of 30 days +/- a couple of days). Much less than the 183 nights for half the year.
@fanfare" Every other weekend" ---- 26 weekends + 4 weeks does not equal over 183 nights. Mother claims them.
@somos321 Are you the custodial parent? Do you have an agreement with the other parent to allow the other parent to claim them--due to divorce or that you live apart and share custody? Did one of you sign a Form 8332?
If there is a signed 8332 then the custodial parent retains the right to file as Head of Household, get earned income credit and the childcare credit + education credits if the child is a full-time college student. The non-custodial parent gets the child tax credit for children under the age of 17.
As far as the IRS is concerned, the custodial parent is the one with whom the child spent the most nights during the tax year--at least 183 nights.