No, child support is not tax deductible for the payer, nor taxable for the recipient.
See IRS Publication 504 for details:
http://www.irs.gov/publications/p504/ar02.html#en_US_2010_publink1000175957
The person who provided physical custody of the child for more than 50% of the year can claim the child as a dependent, regardless of whether or not back child support is owed.
no
File a claim with the County Child Support Devision. Most people who retire have some sort of income that they live on and child support will be taken from those funds.
Do you mean your Grandchild? If the child lived with you, you provided over half of his/her support for the year in question, you meet the relationship test, and the age test, and if no one else claims the child on their tax return. Only one person can claim any other person.
You can only claim a child on your taxes if you provide at least 50% of the FINANCIAL support (through mortgage, food, clothing, education, etc.) for the child. If you provided at least 50% of the support for the child, then you can claim the child for the tax year in which you provided the support.
Keep the claim active with child support enforcement
In most states yes. However, the child will not claim it, rather the custodial parent.
Paying Child Support has nothing to do with any right to claim the child on their return. A divorce agreement or custody agreement usually deals with rights to claim a child on a tax return. If there is no such agreement deciding who get to claim the child then the IRS rules do. Usually the first right is the custodial parent (the person the child lives with). Residency is one of the requirements to claim a dependent.
Because the state provides most of the support for an incarcerated child, a taxpayer may not claim a child if the taxpayer provides less than one half of the child's support.
Only if an order already existed and the claim is still active.
In a case such as this, I suggest that the obligee file an estate claim for the unpaid support.
Contact Child Support Enforcement every 24 months.