If i have joint custody of my son and we switch years for claiming him do i say he lived with me all year

[Phillip1]

Not unless he actually lived with you all of the year. You should enter the accurate number of months.

The rules for determining custodial parent and noncustodial parent take into account the number of nights the child slept in either parents home. The parent who had the child for 183 or more nights is the custodial parent and has the first right to claim the child as a dependent with all of the tax benefits.

If the custody agreement requires the parents alternate years claiming the children as dependents, the noncustodial parent (the parent with the kids for less than 183 days) can claim the dependency exemption and the child tax credit only.

The right to the earned income credit, child and dependent care credit, and to claim head of household filing status are always given to the custodial parent (the parent with the kids for more than 183 days).